标题: 求解(数学) [打印本页] 作者: 1123581321 时间: 2010-9-24 19:15 标题: 求解(数学) 首先谢谢各位的解答。 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 怎么解？ 2)A set of numbers has the property that for any number t in the set, t + 2 is in the set.If –1 is in the set, which of the following must also be in the set?
I.-3 II.1 III.5
A.I only B.II only C.I and II only D.II and III only E.I, II, and III
-3为什么不在这组数里？
3）Joanna bought only $0.15 stamps and $0.29 stamps.How many $0.15 stamps did she buy? (1)She bought $4.40 worth of stamps.
(2)She bought an equal number of $0.15 stamps and $0.29 stamps.
A. Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.
B. Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.
C. BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.
D. EACH statement ALONE is sufficient.
E. Statements (1) and (2) TOGETHER are NOT sufficient.