 # SAT数学考试问答题【基本练习】

2015-07-09 14:21 三立在线 扫下面的二维码即可免费获取TPO模考软件+机经+ETS官方满分作文+托福口语黄金80题+新托福经典加试资料+123个托福考场信息+托福备考各类书籍！ SAT数学考试问答题内容节选：

6. Let the function f be defined by f(x) = x - 1

What is the value of y if y is a positive integer such that 1/3 f(y²) = 5?

7. The amount of time taken to paint a wall is inversely proportional to the number of painters working on the job. If it takes 3 painters 5 days to complete such a job, how many days longer will it take if there are only 2 painters working?

8. Line l and line m lie in the same plane but have no points in common. They are both tangent to a circle

of area 9π. What is the shortest distance between any point on l and any point on m?

9. A box contains 5 chocolates with soft centers, 6 with nut centers, and 11 with hard caramel centers. Three students take turns to take a chocolate at random from the box and eat it. If the probability that all three students take soft centers is 1/x, what is the value of x?

10. At one point in a game the shooting team has a ratio of hits to misses of 5:1. After the next team misses the nest three shots, which are the last in the game, its ratio of hits to misses is 5:2. What is the total number of shots taken by the team in the game?

参考答案：

Explanation:

We can find f(y²) by plugging in to get f(y²) = y²-1 Now we take 1/3 of this value as equal to 5; (y²� 1)/3 =

5; thus y²= 16 and y = 4

Explanation:

For inverse proportions remember the formula x1y1 = x2y2

Here initial painters x days = final painters x days; 3 x 5 = 2 x days

Total days taken will be 15/2 = 7.5, but there is a catch: you were asked how much longer it would take. Initial time was 5 days so it will take 2.5 days longer.

Explanation:

The description tells us that l and m are parallel lines with the circle lying between and touching both.

Area of the circle = πr² = 9 π. Radius = 3 and diameter = 6.

Explanation:

The total number of chocolates to start with is 22. The first student has a chance of 5/22 of taking a soft center. The second student has a only 21 sweets left of which 4 could be soft: his chance is therefore

4/21. Similarly the third student has a chance of 3/20

Total probability is obtained by multiplying all these chances together: (5/22)(4/21)(3/20) = 1/154 [It is best to cancel the terms down rather than using a calculator because we want a fraction not a decimal]

Explanation:

A ratio of 5: 2 means 5x: 2x. Total shots = 7x. The last three shots added one unit to the ratio, and so x = 3.

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