Maths and Stats(Permutations)?

2009-09-06 5:29 am

我想問兩條questions:
1)There is a 6-digit Personal Identifications Number (PIN) encoded in each bank card for security reasons.Find the number of possible PINs?
(a)with repeated digits allowed,
(b)with no repeated digits.

2)Mary has several ways to spend her evening.she can read a book,watch avideo or go for a drink.She can choose between 7 books,5 videos and 3 coffee shops.how many choices does she have if
a)she only takes one activity?
b)she only takes two activities?
c)she takes all three sorts of activities?

Please HELP me the above questions~~..Thank you so much!!

回答 (1)

用戶9112

2009-09-06 6:12 am

✔ 最佳答案

1)There is a 6-digit Personal Identifications Number (PIN) encoded in each bank card for security reasons. Find the number of possible PINs?
a)with repeated digits allowed,
106 = 1,000,000
(b)with no repeated digits.
10x9x8x7x6x5 = 151,200
2)Mary has several ways to spend her evening. She can read a book, watch a video or go for a drink. She can choose between 7 books, 5 videos and 3 coffee shops. How many choices does she have if
a)she only takes one activity?
7 + 5 + 3 = 15
b) she only takes two activities?
7 x 5 + 7 x 3 + 5 x 3 = 35 + 21 + 15 = 71
c) she takes all three sorts of activities?
7 x 5 x 3 = 105

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