问几道SAT概率数学题

问几道SAT概率数学题没学过高中概率,希望讲的详细一些.1.If p,r,m,n,t and s are six different prime numbers greater than 2,and n=p*r*s*m*n*t,how many positive factors,including 1 and n,does n have?2.If someone throws a dice twice,on the first time he gets a points,and on the second he gets b points,what is the probability a/b>1?3.Mr.Jones must choose 4 of the following 5 flavors of jellybean:apple,berry,coconut,kumquat,and lemon,How many different combinations of flavors can Mr.Jones choose?4.有5张卡片,其中的一张A永远都不在两边,问有多少种排列方式