(PUCSP) Dados: DADOS

São conhecidos alguns radioisótopos dos elementos polônio e rádio. Em um experimento, duas amostras de massas diferentes, uma de polônio – 208 e outra de rádio – 224, foram mantidas em uma caixa de chumbo por 18 anos. Ao final desse período, verificou-se que a massa de cada um desses radioisótopos presente no recipiente era igual a 0,025 mg.

Sobre esse experimento foram feitas algumas observações:

I. A desintegração β do ²²⁴Ra resulta no isótopo ²²⁴Pa.

II. A desintegração α do ²⁰⁸Po resulta no isótopo ²⁰⁴Pb.

III. A massa inicial de ²²⁴Ra na caixa de chumbo era de 0,200 mg.

IV. A massa inicial de ²⁰⁸Po na caixa de chumbo era de 0,150 mg.

Dados: Ra (Z = 88); Po (Z = 84); Ac (Z = 89); Pb (Z = 82).

Estão corretas apenas as afirmações:

Garcia tinha-se chegado ao cadáver, levantara o lenço e contemplara por alguns instantes as feições defuntas. Depois, como se a morte espiritualizasse tudo, inclinou-se e beijou-a na testa. Foi nesse momento que Fortunato chegou à porta. Estacou assombrado; não podia ser o beijo da amizade, podia ser o epílogo de um livro adúltero [...].

Entretanto, Garcia inclinou-se ainda para beijar outra vez o cadáver, mas então não pôde mais. O beijo rebentou em soluços, e os olhos não puderam conter as lágrimas, que vieram em borbotões, lágrimas de amor calado, e irremediável desespero. Fortunato, à porta, onde ficara, saboreou tranquilo essa explosão de dor moral que foi longa, muito longa, deliciosamente longa.

                 ASSIS, M. A causa secreta. Disponível em: www.dominiopublico.gov.br. Acesso em: 9 out. 2015.

No fragmento, o narrador adota um ponto de vista que acompanha a perspectiva de Fortunato. O que singulariza esse procedimento narrativo é o registro do(a):

(ENEM 2016) Em uma empresa de móveis, um cliente encomenda um guarda-roupa nas dimensões 220cm de altura, 120cm de largura e 50cm de profundidade. Alguns dias depois, o projetista, com o desenho elaborado na escala 1:8, entra em contato com o cliente para fazer sua apresentação. No momento da impressão, o profissional percebe que o desenho não caberia na folha de papel que costumava usar. Para resolver o problema, configurou a impressora para que a figura fosse reduzida em 20%.

A altura, a largura e a profundidade do desenho impresso para a apresentação serão, respectivamente:

(UERN) Mooresville’s Shining Example (It’s Not Just About the Laptops)

MOORESVILLE, N.C. — Sixty educators from across the nation roamed the halls and ringed the rooms of East Mooresville Intermediate School, searching for the secret formula. They found it in Erin Holsinger’s fifth-grade math class.

There, a boy peering into his school-issued MacBook blitzed through fractions by himself, determined to reach sixth-grade work by winter. Three desks away, a girl was struggling with basic multiplication – only 29 percent right, her screen said – and Ms. Holsinger knelt beside her to assist. Curiosity was fed and embarrassment avoided, as teacher connected with student through emotion far more than Wi-Fi.

As debate continues over whether schools invest wisely in technology – and whether it measurably improves student achievement – Mooresville, a modest community about 20 miles north of Charlotte best known as home to several Nascar teams and drivers, has quietly emerged as the de facto national model of the digital school.

The district’s graduation rate was 91 percent in 2011, up from 80 percent in 2008. On state tests in reading, math and science, an average of 88 percent of students across grades and subjects met proficiency standards, compared with 73 percent three years ago. Attendance is up, dropouts are down. Mooresville ranks 100th out of 115 districts in North Carolina in terms of dollars spent per student – $7,415.89 a year – but it is now third in test scores and second in graduation rates.

“Other districts are doing things, but what we see in Mooresville is the whole package: using the budget, innovating, using data, involvement with the community and leadership,” said Karen Cator, a former Apple executive who is director of educational technology for the United States Department of Education. “There are lessons to be learned.”

Start with math lessons: each student’s MacBook Air is leased from Apple for $215 a year, including warranty, for a total of $1 million; an additional $100,000 a year goes for software. Terry Haas, the district’s chief financial officer, said the money was freed up through “incredibly tough decisions.”

Sixty-five jobs were eliminated, including 37 teachers, which resulted in larger class sizes – in middle schools, it is 30 instead of 18 – but district officials say they can be more efficiently managed because of the technology. Some costly items had become obsolete (like computer labs), though getting rid of others tested the willingness of teachers to embrace the new day: who needs globes in the age of Google Earth?

Families pay $50 a year to subsidize computer repairs, though the fee is waived for those who cannot afford it, about 18 percent of them. Similarly, the district has negotiated a deal so that those without broadband Internet access can buy it for $9.99 a month. Mr. Edwards said the technology had helped close racial performance gaps in a district where 27 percent of the students are minorities and 40 percent are poor enough to receive free or reduced-price lunches.

(The New York Times. February 13, 2012/adaptado) 

The underlined word in the text refers to:

(UTFPR) Determine os valores de x e y na proporção  sabendo que x + y = 144.