请教数学题

11502

1.A certain 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 probability that the passenger will ride in each of the 3 cars?

A.    0
B.    1/9
C.    2/9
D.    1/3
E.    1
2.If 1050 – 74 is written as an integer in base 10 notation, what is the sum of the digits in that integer?

A.  424
B.  433    
C.    440
D.    449
E.    467

11502

fly12404

1)
分母: 3種選擇 玩三次 = 3^3 =27
分子: 三種車都玩到 順序隨便 = 3! =6
6/ 27 = 2/9

2)
題目應該是10^50吧 ?
10^50- 74
10^50次方共有51位數 扣掉74
會剩下50位數(因為第一個1退到後面變成9)
也就是9999999999..........26 (48個9 後兩位為26)
48x9 + 2 +6 =440
: )

11502

谢啦