单选题
单选题
To the nearest million, how many more students were enrolled in school—both public and private, prek-12—in 1970 than in 1988?
【正确答案】
B
【答案解析】Reading from the top graph, we get the following enrollment figures:
1970 1988
Public PreK-8 33,000,000 28,000,000
Public 9-12 13,000,000 12,000,000
Private PreK-8 4,000,000 4,000,000
Private 9-12 1,000,000 1,000,000
Total 51,000,000 45,000,000
51,000,000 -45,000,000 = 6,000,000.
1970 1988
Public PreK-8 33,000,000 28,000,000
Public 9-12 13,000,000 12,000,000
Private PreK-8 4,000,000 4,000,000
Private 9-12 1,000,000 1,000,000
Total 51,000,000 45,000,000
51,000,000 -45,000,000 = 6,000,000.
单选题
In 1988 there were 40,000,000 public school students in the United States, of whom 22% lived in the West. Approximately, how many public school students are projected to be living in the West in 2008?
【正确答案】
B
【答案解析】In 1988, 8,800,000 (22% of 40,000,000) students lived in the West. From 1988-1998 this figure increased by 27%—for simplicity use 25%: an additional 2,200,000 students; so the total was then 11,000,000. The projected increase from 1998-2008 is about 10%, so the number will grow by 1,100,000 to 12,100,000.
单选题
If a and b are the lengths of the legs of a right tri-angle whose hypotenuse is 10 and whose area is 20, what is the value of (a + b)2?
【正确答案】
D
【答案解析】Expand:
(a + b)2 = a2 + 2ab + b2 = (a2 + b2) + 2ab.
By the Pythagorean theorem,
a2+b2= 102=100; and since the area is 20,
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Then
(a2+b2)+2ab= 100+80=180.
[*]
(a + b)2 = a2 + 2ab + b2 = (a2 + b2) + 2ab.
By the Pythagorean theorem,
a2+b2= 102=100; and since the area is 20,
[*]
Then
(a2+b2)+2ab= 100+80=180.
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