Questão de Estatística

Considerando que ᡐ⡩, ᡐ⡰, ᡐ⡱, ᡐ⡲ representa uma amostra aleatória simples de tamanho ᡦ = 4 retirada de uma população normal com média † e desvio padrão ‡, julgue os itens que se seguem. 〥ㄗ⡹〥ㄘ As estatísticas ᡆ⡩ = ᡐ⡩, ᡆ⡰ = e ᡆ⡱ = são ⡰ ⡱ estimadores não viciados da média populacional †. 䙦〥 ⡹ゑ䙧ㄘ ᡃ = 㒕 ㄗ segue uma distribuição normal padrão. 110 ぉㄘ Russia is making heaps of money from oil, but there is a way to stop that The United States and its allies are leaning heavily on economic sanctions to punish Russia for its invasion of Ukraine. But a key element in that strategy, restrictions on Russian oil exports, mostly appears to be causing pain for ordinary people in other countries. European nations, in particular, are causing considerable damage to their own economies without reducing Russia’s oil revenue. Nations seeking to help Ukraine have focused on reducing Russia’s energy exports instead of reducing Russia’s earnings from energy exports. Russia is exporting less oil but, in a perverse twist, it is earning more money. The sanctions have raised prices, more than offsetting the decline in exports. In May 2022, Russia earned 883 million euros per day from oil exports, up from 633 million euros per day in May 2021. New sanctions that the European Union and Britain have agreed to impose on Russia by year’s end are likely to drive oil prices even higher. Some analysts warn that the price for a barrel of oil could exceed $ 200, well above the spike in the early weeks of the war, when oil prices topped out around $ 124. Internet: <www.nytimes.com> (adapted).