Foram encontradas 390 questões.
Considere o problema de maximizar !$ f(x, \, y) \, = \, ax \, + \, y !$ com !$ a \, > \, 0 !$, sujeito às restrições: !$ x \, + \, y \, -5 \, \le \, 0, \, y \, \le \, 2 !$. Julgue a seguinte afirmativa:
Item 3 - Se a primeira restrição acima mudasse para !$ bx \, + \, y \, - \, 5 \le \, 0 !$, com !$ 0 \, < \, b \, < 1 !$, então a solução seria !$ (x, \, y) \, = \, (3, \, 5) !$.
Provas
Questão presente nas seguintes provas
Um economista deseja avaliar o consumo de carne bovina em 2 estados brasileiros: Rio Grande do Sul (RS) e Rio Grande do Norte (RN). Para tanto, ele seleciona uma amostra de 50.000 unidades de consumo, 35.000 localizadas no Rio Grande do Sul (primeira sub-amostra) e 15.000 no Rio Grande do Norte (segunda sub-amostra). Inicialmente, o economista preferiu trabalhar com as sub-amostras em separado.
Para as duas sub-amostras ele estima a Curva de Engel para o consumo de carne bovina pelo método de Mínimos Quadrados Ordinários. Os resultados das regressões estão abaixo, em que os erros-padrão estão entre parênteses:
[Para a resolução desta questão talvez lhe seja útil saber que se Z tem distribuição normal padrão, então P(|Z|>1,645)=0,10 e P(|Z|>1,96)=0,05]
In (consumo) = 0,30 + 1,15 ln(renda) - RS (1)
(0,25) (0,04)
R2 = 0,45 e n=35.000
In (consumo) = 0,80 + 0,67 ln(renda) - RN (2)
(0,65) (0,07)
R2 = 0,38 e n=15.000 ,
em que ln(consumo) é o logaritmo natural do consumo de carne bovina, em quilogramas, e ln(renda) é o logaritmo natural da renda total do domicílio, em milhares de reais. Todas as suposições usuais acerca do modelo de regressão linear clássico são satisfeitas.
Com base nos resultados acima, e supondo que a amostra é suficientemente grande para que aproximações assintóticas sejam válidas, é correto afirmar que:
Item 1 - De acordo com os resultados das regressões, para um nível de renda igual a R$ 1,00, o consumo de carne no Rio Grande do Sul será maior do que no Rio Grande do Norte, mantendo todas as demais condições constantes;
Provas
Questão presente nas seguintes provas
Classifique a alternativa como verdadeira (V) ou falsa (F):
Item 1 - No sistema de contas nacionais, a venda de estoques não afeta a renda;
Provas
Questão presente nas seguintes provas
Classifique a afirmativa como verdadeira (V) ou falsa (F):
Item 2 - Uma economia que sustenta uma taxa mais elevada de progresso tecnológico ultrapassará, em última instância, todas as outras economias.
Provas
Questão presente nas seguintes provas
Text 2
Pandemic disease
Never again
As the Ebola epidemic draws gradually to its close, how should the world arm itself against the risks of insurgent infections?
Mar 21st 2015 | From the print edition
THE outbreak of Ebola fever brought to the world’s attention on March 22nd 2014 by Médecins Sans Frontières, an international charity, has infected some 25,000 people and killed more than 10,000 of them—almost all in Guinea, Liberia and Sierra Leone. It is abating. Liberia is close to declaring itself free of the virus and infection rates are falling in Sierra Leone. But it is not over yet, for in Guinea Ebola still kills dozens of people a week.
Moreover, the aftermath will harm the three countries’ economies, costing at least $1.6 billion in forgone economic growth this year, according to the World Bank.
Though it could have been a lot worse (at the height of the crisis some epidemiologists were talking of hundreds of thousands of deaths) it might also have been a lot better.
Previous Ebola outbreaks killed dozens or hundreds. The whole episode therefore suggests that the world’s defences against epidemics, though they have been strengthened since the rapid spread of SARS in 2002 and 2003 demonstrated their weaknesses, could do with reinforcing still further.
The prime directive of epidemic prevention is early detection. That means good surveillance. Unfortunately, only 64 of the 194 members of the World Health Organisation (WHO) have surveillance procedures, laboratories and data-management capabilities good enough to fulfil their obligations under an agreement known as the International Health Regulations. This, though, is changing. In Africa, Ethiopia, Rwanda and Uganda have sharpened up. So has Vietnam. America is now helping 30 other countries, including the three affected by Ebola, to follow suit while, at the same time, improving their networks of clinics. Groups of neighbours are also coming together to form regional surveillance networks that can follow outbreaks across borders. Researchers in Cambodia, China, Indonesia, Laos, Thailand and Vietnam, for example, have formed what they call the Asian Partnership on Emerging Infectious Diseases Research.
Along with early detection, the world needs to get better at responding—both institutionally and technologically. The WHO, notoriously slow off the mark when it came to Ebola, is widely regarded as too ponderous and bureaucratic to react with the speed needed to nip an emerging epidemic in the bud. There is talk of setting up a specialist international epidemic-prevention organisation. Bill Gates, a philanthropist whose foundation does a lot of work on disease control in poor countries, encourages this idea in this week’s New England Journal of Medicine. He notes that epidemics and war are similarly costly of blood and treasure, but that only war is taken seriously by politicians—at least in terms of preparations such as standing armies. As if to prove the point, the threat of bioterrorism has been one motive for what preparations have been put in place.
An army, of course, needs weapons. And, in the case of epidemics, it is important to think about what those might be. The temptation is to put money into high-profile areas like vaccines and drugs. It may, though, be more useful to concentrate on diagnosis, because this can stop people spreading a disease. The science of diagnostic testing is advancing rapidly, making it easier to come up quickly with a test for a new pathogen. That, Mr Gates believes, presents an opportunity. But it is one, he says, which requires the establishment of a rapid approval and procurement process, so that diagnostic tests can be made available quickly during outbreaks. They also need to be portable, like pregnancy tests, to keep people out of clinics where they might otherwise spread infection.
Drugs and vaccines are still important, of course. Research is going on into ways to make new vaccines quickly, so trials can start within days of an outbreak. Modern biological techniques mean a pathogen’s genome can be copied and stuck into other cells to turn out proteins which might be used as a vaccine’s active ingredients. Once a vaccine has been identified, the same techniques could be used to make it quickly, and possibly locally if a portable factory were shipped to an affected area.
The sinews of war
But none of this rapid response can happen without cash. One lesson of an earlier incident, the H1N1 influenza (“swine flu”) pandemic of 2009, was the lack of a contingency fund to deal with such things. This is a problem Jim Yong Kim, president of the World Bank, is determined to solve. He has been meeting with politicians and the private sector to advance the case for a “global pandemic emergency financing facility”.
One more modest possibility is that pools of research funding could be set up in advance, along with agreed research protocols, allowing health studies to start more quickly. An existing example of this is a fund created by the Wellcome Trust, a British medical charity.
Even on the coldest of calculations, a contingency fund would be a wise precaution. The damage caused by Ebola to west Africa’s economy is trivial compared with the cost of, say, a global influenza pandemic. The World Bank reckons that might reduce global economic activity by almost 5%. How many would die would depend on the virus’s virulence. But even a 1% death rate, for something that was truly worldwide, would add up to millions. That is too much blood, and too much treasure, for politicians to ignore.
From the print edition: Science and technology
We understand from the text that:
Item 2 - The majority of the members of WHO have effective surveillance procedures;
Provas
Questão presente nas seguintes provas
Classifique a alternativa como verdadeira (V) ou falsa (F):
Item 0 - Déficits orçamentários do Tesouro Nacional financiados por meio de empréstimos junto ao Banco Central aumentam a base monetária;
Provas
Questão presente nas seguintes provas
Sobre a economia brasileira e a política econômica na década de 1950, é correto afirmar:
Item 3 - A taxa de investimento cresceu entre 1955 e 1960, o que contribui para explicar o crescimento expressivo do PIB.
Provas
Questão presente nas seguintes provas
Em uma festa com 50 participantes, somente 6 não ingerem bebida alcoólica. Sabe-se que 20 bebem vodka, 21 bebem martini e 22 bebem cerveja. Sabe-se também que 9 bebem vodka e martini, 8 bebem vodka e cerveja e 7 bebem martini e cerveja. Indique quais das seguintes alternativas são verdadeiras e quais são falsas:
Item 3 - 23 participantes não bebem Martini;
Provas
Questão presente nas seguintes provas
Com relação à teoria dos custos, é correto afirmar que:
Item 4 - Sendo C(q1, q2) o custo da produção conjunta de dois bens q1 e q2, C(q1, 0) o custo de produzir q1 isoladamente e C(0, q2) o custo de produzir q2 isoladamente, se [C(q1, 0) + C(0, q2) - C(q1, q2)]/C(q1, q2) < 0, então há deseconomias de escopo.
Provas
Questão presente nas seguintes provas
Considere a seguinte função: !$ f(x) \, = \, 3x^4 \, -4x^3 \, -36x^2 \, + \, 5 !$]. Classifique a seguinte alternativa como verdadeira ou falsa:
Item 0 - A função é crescente no intervalo !$ [0, \, + \, \infty[ \, ; !$
Provas
Questão presente nas seguintes provas
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