求助Prep数学

ilovemaple2

1.How many different prime numbers are factors of the positive integer n ?
 
(1) Four different prime numbers are factors of 2n. 
 

(2) Four different prime numbers are factors of n .

答案是B，我觉得选D咧。

2.Is zero an even number?

3.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 factor of h(100) + 1, then p is

(A) between 2 and 10

(B) between 10 and 20

(C) between 20 and 30

(D) between 30 and 40

(E) greater than 40

4.A furniture dealer purchased a desk for $150 and then set the selling price equal to the purchase price plus a markup that was40 percent of the selling price.  If the dealer sold the desk at the selling price, what was the amount of the dealer's gross profit from the purchase and the sale of the desk?

(A)  $40

(B)  $60

(C)  $80

(D)  $90

(E) $100

此题为啥不选B呢？

谢谢各位了~~o(∩_∩)o...

mymengming

发问请在标题上注明题号，谢谢

1.How many different prime numbers are factors of the positive integer n ?
 
(1) Four different prime numbers are factors of 2n.

(2) Four different prime numbers are factors of n .

答案是B，我觉得选D咧。

（1）如果2也是n的因子，则n有4个质数因子

如果2不是，则只有3个

2.Is zero an even number?

是

3.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 factor of h(100) + 1, then p is

(A) between 2 and 10

(B) between 10 and 20

(C) between 20 and 30

(D) between 30 and 40

(E) greater than 40

http://forum.chasedream.com/dispbbs.asp?BoardID=22&replyID=1733108&id=183630&skin=0

4.A furniture dealer purchased a desk for $150 and then set the selling price equal to the purchase price plus a markup that was40 percent of the selling price.  If
the dealer sold the desk at the selling price, what was the amount of
the dealer's gross profit from the purchase and the sale of the desk?

(A)  $40

(B)  $60

(C)  $80

(D)  $90

(E) $100

此题为啥不选B呢？

x=150+40%x

x=250

250*40%=100

ilovemaple2

Thanks a million~