数学求助，大家帮忙啊，附英文原题，答案

9.4   9.9   9.9   9.9  10.0  10.2  10.2  10.5

The mean and the standard deviation of the 8 numbers shown are 10.0 and 0.3, respectively. What percent of the 8 numbers are within 1 standard deviation of mean?

Answer: 75%

A certain list consists of several different integers. Is the product of all the integers in the list positive?

1) The product of the greatest and smallest of the integers in the list is positive

2) There is an even number of integers in the list

Answer: C

Which of the following lists the number of points at which a circle can intersct a triangle?

A  2 and 6 only

B  2, 4, and 6only

C  1, 2, 3, and 6 only

D 1, 2, 3, 4and 6only

E 1,2,3,4,5and 6

E correct

Is the measure of one of the interior angles of quadrilateral ABCD equal to 60degrees?

1)      Two of the interior angles of ABCD are right angles.

2)      The degree measure of angle ABC is twice the degree measure of angle BCD

Answer: E

For every positive even integer n, the function h(n) is defined to be the product of all the even integers from 2 to n, inclusive. If p is the smallest prime number factor of h(100)+1, then p is

A between 2-10

B between 10-20

C between 20-30

D between 30-40

E greater than 40

E correct

The perimeter of a certain isosceles right triangle is 16+16根号2, What is the length of the hypotenuse of the triangle?

Answer: 16

A boat traveled upstream a distance of 90 miles at an average speed of (v-3) miles per hour and then traveled the same distance downsream at an average speed of (V+3) miles perhour. If the trop upstream took half an hour longer than trip downstream, how man hours did it take the boat to travel downstream?

Answer:2.5

9.4   9.9   9.9   9.9  10.0  10.2  10.2  10.5

The mean and the standard deviation of the 8 numbers shown are 10.0 and 0.3, respectively. What percent of the 8 numbers are within 1 standard deviation of mean?

 落在(9.7  10.3)这个区间的有6个=>6/8=75%

 落在(9.7  10.3)这个区间的有6个=>6/8=75%

Answer: 75%

A certain list consists of several different integers. Is the product of all the integers in the list positive?

1) The product of the greatest and smallest of the integers in the list is positive

2) There is an even number of integers in the list

 1 说明这个list同号。但不能判断是正号，还是负号（个数为奇数时product of all<0,偶数个时>0)

 2.说明了是偶数个

所以1，2可以判断一定>0

 1 说明这个list同号。但不能判断是正号，还是负号（个数为奇数时product of all<0,偶数个时>0)

 2.说明了是偶数个

所以1，2可以判断一定>0

Answer: C

Which of the following lists the number of points at which a circle can intersct a triangle?

A  2 and 6 only

B  2, 4, and 6only

C  1, 2, 3, and 6 only

D 1, 2, 3, 4and 6only

E 1,2,3,4,5and 6

E correct

 一个圆和一个三角形能有几个交点。。E

随便画就行

 一个圆和一个三角形能有几个交点。。E

随便画就行

Is the measure of one of the interior angles of quadrilateral ABCD equal to 60degrees?

1)      Two of the interior angles of ABCD are right angles.

2)      The degree measure of angle ABC is twice the degree measure of angle BCD

Answer: E

 画图。。

 画图。。

For every positive even integer n, the function h(n) is defined to be the product of all the even integers from 2 to n, inclusive. If p is the smallest prime number factor of h(100)+1, then p is

A between 2-10

B between 10-20

C between 20-30

D between 30-40

E greater than 40

E correct

 h(100)+1和h(100) 互质，不能有相同的因子，所以只要找到h100最大的FACTOR就行

显然h(100)=2*4*....*100 最小的质因子是47.所以答案E

 h(100)+1和h(100) 互质，不能有相同的因子，所以只要找到h100最大的FACTOR就行

显然h(100)=2*4*....*100 最小的质因子是47.所以答案E

The perimeter of a certain isosceles right triangle is 16+16根号2, What is the length of the hypotenuse of the triangle?

Answer: 16

 列方程，勾股定理。。。hypotenuse是x，直角边是 根号2/2

 列方程，勾股定理。。。hypotenuse是x，直角边是 根号2/2

A boat traveled upstream a distance of 90 miles at an average speed of (v-3) miles per hour and then traveled the same distance downsream at an average speed of (V+3) miles perhour. If the trop upstream took half an hour longer than trip downstream, how man hours did it take the boat to travel downstream?

Answer:2.5

列方程啊。。。90/(v-3)=90/(v+3)+0.5 算v