请教GWD两道数学题
祝大家新年快乐先，不好意思又要麻烦大家两道gwd数学。
1。joanna bought only $0.15 stamps and $0.29 stamps. How many $0.15 stamps did she buy?
(1) she bought $4.4 worth of stamps
(2) she bought an equal number of $0.15 stamps and $0.29 stamps
答案是d，我选了a，我觉得（2）推不出来啊？？
2。Acertain roller coaster has 3 cars, and a passenger is equally likely to ride in any 1 of the 3 cars each time that passenger rides the roller coaster. If a certain passenger is to ride the roller coaster 3 times, what is the probabability that the passenger will ride in each of the 3 cars.
A.0
B.1/9
C.2/9
D1/3
E.1
当年上学的时候概率论和数理统计没学好，现在也经常一头雾水，求教NN这道题怎么做？另外，有关GMAT概率部分看什么复习材料比较好呢？多谢
