Question 983812: Pls help me work out this problem
Using the digits 1,2,3 and 5, how many 4 digit numbers can be formed if
a) the first digit must be 1 and repetition of the digits is allowed?
b) the first digit must be 1 and repetition of the digits is not allowed?
c) the number must be divisible by 2 and repetion is allowed?
d) the number must be divisible by 2 and repetition is not allowed?
Answer by macston(5194)   (Show Source):
You can put this solution on YOUR website! a) the first digit must be 1 and repetition of the digits is allowed?
There is 1 possible first digit, 4 second, 4 third and 4 fourth
1 x 4 x 4 x 4=64
ANSWER: 64 possible four digit numbers with 1 as first digit.
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b) the first digit must be 1 and repetition of the digits is not allowed?
One possible first digit, 3 second, 2 third , 1 fourth
1 x 3 x 2 x 1=6
ANSWER: There are 6 possible numbers.
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c) the number must be divisible by 2 and repetition is allowed?
4 possible first digits, 4 possible second, 4 third, 1 fourth
4 x 4 x 4 x 1=64
ANSWER 64 possible numbers
.
d) the number must be divisible by 2 and repetition is not allowed?
3 possible first digits, 2 second, 1 third, 1 fourth
3 x 2 x 1 x 1=6
ANSWER: 6 possible numbers
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