3 questions need help...thanks a lot

RainaLu

1) If n is a positive integer less than 200 and 14n/60 is an integer, then n has how many differernt postive prime factors?

The key is 3. But I thought it should 4, which are 1,2,3,5.

2) Is m+z>0

   (1) m-3z>0

   (2) 4z-m>0

Key: both together are sufficient. I don't understand why, I though it be answer E.

3) Of the 60 animals on a certain farm, 2/3 are either pigs or cows. How many of the animals are cows?

    (1) The farm has more than twice as many cows as it has pigs.

    (2) The farm has more than 12 pigs.

Key: both together are sufficient. Still can't understand why, thought should be E.

jh1904

1)  1 is not a prime number. Only 2,3,5 are.

2) I also think the answer is E.

3) 60*2/3 = 40 : cows + pigs =40.

With condition 1, c>2p, c>40*2/3, c>26, p<=13

With condition 2, p>=13

With condition 1 and 2, p can only be 13 and c can only be 27.

愁予

(2)那两条件连立解不等式方程组得出m>0,z>0。

RainaLu

谢谢!