Foram encontradas 400 questões.
A variável aleatória discreta X assume apenas os valores 0, 1, 2, 3, 4 e 5. A função densidade de probabilidade de X é dada por
!$ P(X \, = \, 0) \, = \, P(X \, = \, 1) \, = \, P(X \, = \, 2) \, = \, P(X \, = \, 3) \, = \, \alpha \\ \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, P(X \, = \, 4) \, = \, P(X \, = \, 5) \, = \, b \\ \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, P(X \, \ge \, 2) \, = \, 3P(X \, < \, 2) !$
E[ . ] e V[ . ] denotam, respectivamente, esperança e variância. Julgue a seguinte alternativa:
Item 2 - V[X] = 12.
Provas
Questão presente nas seguintes provas
Text 1
Excerpts from:
The “CSI effect”
Television dramas that rely on forensic science to solve crimes are affecting the administration of justice
Apr 22nd 2010 | From The Economist print edition
OPENING a new training centre in forensic science (...) at the University of Glamorgan in South Wales recently, Bernard Knight, formerly one of Britain’s chief pathologists, said that because of television crime dramas, jurors today expect more categorical proof than forensic science is capable of delivering. And when it comes to the gulf between reality and fiction, Dr Knight knows what he is talking about: besides 43 years’ experience of attending crime scenes, he has also written dozens of crime novels.
The upshot of this is that a new phrase has entered the criminological lexicon: the “CSI effect” after shows such as “CSI: Crime Scene Investigation”. In 2008 Monica Robbers, an American criminologist, defined it as “the phenomenon in which jurors hold unrealistic expectations of forensic evidence and investigation techniques, and have an increased interest in the discipline of forensic science.”
Now another American researcher has demonstrated that the “CSI effect” is indeed real. Evan Durnal of the University of Central Missouri’s Criminal Justice Department has collected evidence from a number of studies to show that exposure to television drama series that focus on forensic science has altered the American legal system in complex and far-reaching ways. His conclusions have just been published in Forensic Science International.
The most obvious symptom of the CSI effect is that jurors think they have a thorough understanding of science they have seen presented on television, when they do not. Mr Durnal cites one case of jurors in a murder trial who, having noticed that a bloody coat introduced as evidence had not been tested for DNA, brought this fact to the judge’s attention. Since the defendant had admitted being present at the murder scene, such tests would have thrown no light on the identity of the true culprit. The judge observed that, thanks to television, jurors knew what DNA tests could do, but not when it was appropriate to use them.
(...)
Criminals watch television too, and there is evidence they are also changing their behaviour. Most of the techniques used in crime shows are, after all, at least grounded in truth. Bleach, which destroys DNA, is now more likely to be used by murderers to cover their tracks. The wearing of gloves is more common, as is the taping shut—rather than the DNA-laden licking—of envelopes. Investigators comb crime scenes ever more finely for new kinds of evidence, which is creating problems with the tracking and storage of evidence, so that even as the criminals leave fewer traces of themselves behind, a backlog of cold-case evidence is building up.
The CSI effect can also be positive, however. In one case in Virginia jurors asked the judge if a cigarette butt had been tested for possible DNA matches to the defendant in a murder trial. It had, but the defence lawyers had failed to introduce the DNA test results as evidence. When they did, those results exonerated the defendant, who was acquitted.
Mr Durnal does not blame the makers of the television shows for the phenomenon, because they have never claimed their shows are completely accurate. (Forensic scientists do not usually wield guns or arrest people, for one thing, and tests that take minutes on television may take weeks to process in real life.) He argues that the CSI effect is born of a longing to believe that desirable, clever and morally unimpeachable individuals are fighting to clear the names of the innocent and put the bad guys behind bars. In that respect, unfortunately, life does not always imitate art.
According to the text:
Item 3 - evidence is now easier to store;
Provas
Questão presente nas seguintes provas
Analise a alternativa abaixo, tomando como base a teoria dos ciclos reais:
Item 1 - A substituição intertemporal de mão-de-obra é o canal de transmissão através do qual choques tecnológicos afetam o nível de emprego.
Provas
Questão presente nas seguintes provas
Text 2
Excerpts from:
Small eruption in Iceland
A cloud of ash from an Icelandic volcano shut European airspace for several days. Our first article examines the science of volcanic emissions.
Our second looks at the past week's disruption of travel
Apr 22nd 2010 | From The Economist print edition
SOME natural disasters, like the Indian Ocean tsunami of 2004, strike out of the blue. Only with hindsight do they come to look like the sort of thing people should have been prepared for. Other events get dress rehearsals. The eruption of Eyjafjallajokull in the south of Iceland was one of these. In February 2008 officials from air-traffic-control services across Europe, as well as representatives of weather services and airlines, ran an exercise that simulated a strikingly similar eruption. The volcano they chose was not Eyjafjallajokull, but its neighbour, Katla; the weather conditions were not quite the same. But the procedures were.
(...)
If the exercise two years ago did not capture the range of problems that an Icelandic volcano might cause, it did show that the general situation was entirely foreseeable. A ridge of submerged mountains runs down the middle of the Atlantic Ocean; Iceland is the result of a “hotspot” in which material rises from deep within the Earth, pushing part of this ridge up into the air. Both hotspots and mid-ocean ridges are volcanic, so Iceland is doubly so. It boasts a fearsome array of volcanoes, 33 of which have erupted once or more since the end of the last ice age, around 12,000 years ago.
As these volcanoes go, Eyjafjallajokull is neither very big nor particularly prolific. It has erupted only three times since Iceland was settled in the ninth century. That is why the air-traffic exercise planners chose Katla, 25km (16 miles) away; it typically erupts every 30-80 years, and in a much more spectacular way. But a combination of circumstances meant that, though comparatively small, Eyjafjallajokull's current eruption punched above its weight in the ash-production league in its early days, emitting much more fine ash than is normal. Fine ash can travel farther than the heavier stuff, but still does a lot of harm to engines if encountered in significant quantities.
(...)
Katla is not the worst that Iceland can do. Its volcanoes do not have the explosive oomph of some eruptions in the “ring of fire” around the Pacific, such as those of Tambora and Krakatoa in the 19th century, let alone the prehistoric eruptions of Taupo, in New Zealand, and Toba, in Indonesia, which were large enough to have severe, if short-lived, effects on the global climate (...) But the eruption of Oraefajokull, in the south-east of the island, in 1362 is thought by some to have eclipsed that of Mount Vesuvius which destroyed Pompeii and Herculaneum in 79AD. It may have been the biggest bang in Europe since the eruption in the 17th century BC of Santorini, which devastated the Minoan civilisation on nearby Crete. Nor is explosive power the only measure of a volcano's spitefulness. The eruption of Laki, an Icelandic volcanic fissure, in 1783 sent poisonous gases across Europe.
Another concern is that Iceland's volcanoes, especially those under its central ice cap—which, other things being equal, will produce more explosive plumes if they break through—seem to show a cycle in activity, perhaps due to the hotspot that feeds them.
On this reading of the record, activity can be expected to increase for the next 40 years or so. The past few decades have been one of the quiet patches. It seems likely that the first 50 years of jet travel across the North Atlantic enjoyed particularly clear skies.
We can infer from the text that
Item 0 - all Icelandic volcanoes have roughly the same explosive power;
Provas
Questão presente nas seguintes provas
Sobre a Teoria do Consumidor, assinale Verdadeiro ou Falso na alternativa abaixo:
Item 1 - Para preferências homotéticas a taxa marginal de substituição depende somente da razão consumida entre as quantidades dos dois bens e não das quantidades totais de cada bem.
Provas
Questão presente nas seguintes provas
Considere uma economia com as seguintes características:
!$ \bullet !$ Surgem N novos consumidores idênticos (N>0) no início de cada período de tempo.
!$ \bullet !$ O governo realiza gastos per capita constantes no tempo, que são financiados através de impostos de montante fixo (“lump-sum”) ou de aumento da dívida pública. A restrição orçamentária intertemporal do governo é satisfeita de tal forma que eventuais reduções nos impostos financiadas por aumento da dívida pública em certo período t são necessariamente compensadas por aumentos nos impostos em algum momento após t. O valor total arrecadado pelo governo em cada período é cobrado em parcelas iguais de todos os indivíduos existentes no período.
!$ \bullet !$ Os indivíduos de todas as gerações possuem preferências idênticas, descontam o futuro à taxa !$ \beta !$ (0<!$ \beta !$<1), têm previsão perfeita e vivem por exatamente H períodos. Em cada período, os indivíduos recebem uma renda constante, pagam o imposto de montante fixo e optam entre consumir ou poupar sua renda e riqueza acumulada. Os indivíduos podem transferir renda/deixar heranças para as gerações mais novas, se assim desejarem.
!$ \bullet !$ Os mercados de crédito são perfeitos.
Com base nessas informações, julgue a seguinte alternativa:
Item 1 - Se !$ \infty \, \rightarrow !$ e cada consumidor aufere a mesma utilidade de seu próprio consumo e do consumo das gerações mais novas, a equivalência ricardiana é válida.
Provas
Questão presente nas seguintes provas
O país A transaciona bens com os países B e C, sendo 60% de seu comércio exterior realizado com o país B e 40% com o país C. Os seguintes dados para os anos 1 e 2 são conhecidos:
| Ano 1 | Ano 2 | |
| Preço de uma unidade da moeda do país B em unidades da moeda do país A (média no ano) | 2,00 | 2,40 |
| Preço de uma unidade da moeda do país C em unidades da moeda do país A (média no ano) | 4,00 | 3,60 |
| Índice de preço do país A (média no ano) | 100 | 110 |
| Índice de preço do país B (média no ano) | 50 | 50 |
| Índice de preço do país C (média no ano) | 100 | 115 |
Com base nessas informações, julgue a seguinte alternativa:
Item 1 - Para as economias em questão, a condição de paridade do poder de compra não é válida no curto prazo, mas pode ser válida no longo prazo.
Provas
Questão presente nas seguintes provas
Text 2
Excerpts from:
Small eruption in Iceland
A cloud of ash from an Icelandic volcano shut European airspace for several days. Our first article examines the science of volcanic emissions.
Our second looks at the past week's disruption of travel
Apr 22nd 2010 | From The Economist print edition
SOME natural disasters, like the Indian Ocean tsunami of 2004, strike out of the blue. Only with hindsight do they come to look like the sort of thing people should have been prepared for. Other events get dress rehearsals. The eruption of Eyjafjallajokull in the south of Iceland was one of these. In February 2008 officials from air-traffic-control services across Europe, as well as representatives of weather services and airlines, ran an exercise that simulated a strikingly similar eruption. The volcano they chose was not Eyjafjallajokull, but its neighbour, Katla; the weather conditions were not quite the same. But the procedures were.
(...)
If the exercise two years ago did not capture the range of problems that an Icelandic volcano might cause, it did show that the general situation was entirely foreseeable. A ridge of submerged mountains runs down the middle of the Atlantic Ocean; Iceland is the result of a “hotspot” in which material rises from deep within the Earth, pushing part of this ridge up into the air. Both hotspots and mid-ocean ridges are volcanic, so Iceland is doubly so. It boasts a fearsome array of volcanoes, 33 of which have erupted once or more since the end of the last ice age, around 12,000 years ago.
As these volcanoes go, Eyjafjallajokull is neither very big nor particularly prolific. It has erupted only three times since Iceland was settled in the ninth century. That is why the air-traffic exercise planners chose Katla, 25km (16 miles) away; it typically erupts every 30-80 years, and in a much more spectacular way. But a combination of circumstances meant that, though comparatively small, Eyjafjallajokull's current eruption punched above its weight in the ash-production league in its early days, emitting much more fine ash than is normal. Fine ash can travel farther than the heavier stuff, but still does a lot of harm to engines if encountered in significant quantities.
(...)
Katla is not the worst that Iceland can do. Its volcanoes do not have the explosive oomph of some eruptions in the “ring of fire” around the Pacific, such as those of Tambora and Krakatoa in the 19th century, let alone the prehistoric eruptions of Taupo, in New Zealand, and Toba, in Indonesia, which were large enough to have severe, if short-lived, effects on the global climate (...) But the eruption of Oraefajokull, in the south-east of the island, in 1362 is thought by some to have eclipsed that of Mount Vesuvius which destroyed Pompeii and Herculaneum in 79AD. It may have been the biggest bang in Europe since the eruption in the 17th century BC of Santorini, which devastated the Minoan civilisation on nearby Crete. Nor is explosive power the only measure of a volcano's spitefulness. The eruption of Laki, an Icelandic volcanic fissure, in 1783 sent poisonous gases across Europe.
Another concern is that Iceland's volcanoes, especially those under its central ice cap—which, other things being equal, will produce more explosive plumes if they break through—seem to show a cycle in activity, perhaps due to the hotspot that feeds them.
On this reading of the record, activity can be expected to increase for the next 40 years or so. The past few decades have been one of the quiet patches. It seems likely that the first 50 years of jet travel across the North Atlantic enjoyed particularly clear skies.
According to the text:
Item 2 - the eruption of Mount Vesuvius destroyed Pompeii in 1362;
Provas
Questão presente nas seguintes provas
Sobre a Teoria da Produção analise a alternativa abaixo:
Item 0 - A função de produção que exibe retornos constantes de escala é uma função homogênea do grau 0.
Provas
Questão presente nas seguintes provas
Com relação às decisões dos agentes sob incerteza, é possível afirmar que:
Item 0 - Se Pedro define sua utilidade a partir de um nível de riqueza W, de tal modo que sua função utilidade é dada por !$ U(W) \, = \, 1 \, - \, CW^{-a} !$, em que a e C são constantes positivas, então Pedro é avesso ao risco.
Provas
Questão presente nas seguintes provas
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