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?
A. 3,000,000 B. 6,000,000 C. 10,000,000
D. 44,000,000 E. 51,000,000
A. 3,000,000 B. 6,000,000 C. 10,000,000
D. 44,000,000 E. 51,000,000
【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?
A. 9,000,000 B. 12,000,000 C. 15,000,000
D. 24,000,000 E. 66,000,000
A. 9,000,000 B. 12,000,000 C. 15,000,000
D. 24,000,000 E. 66,000,000
【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?
A. 100B. 120C. 140D. 180E. 200
A. 100B. 120C. 140D. 180E. 200
【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,
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.