大家好:
請教大家數學問題
陳向東P260
13.Each integer from 1 to 50 whose units digit is a 3 is written on a slip of
paper and placed in a box. If two slips of paper are drawn at random, what is
the probability that both the numbers picked are prime?
14. A jar contains 20 marbles: 4 red, 6 white, and 10 blue. If you remove
marbles one at a time, randomly, what is the minimum number that must removed
to be certain that you have at least 2 marbles of each colar?
A.6 B.10 C.12 D.16 E.18(Ans.)
P261 18
George earned 80, 85 and 90 on the first three tests in his G class.Becoz
he didn't have time to study, he decided to guess randomly on the final test.
That test has ten true-false questions, each worth 10 points. What is the
probability his final average is more than 85?
A. 12/2的八次方 B. 11/2的八次方 C. 12/1024
D. 11/1024(Ans.) E. 0.5
感謝!