How many even numbers of 4 digits can be formed with the figures 3,4,7,8 if (a) no figure is repeated, (b) if repetitions are allowed

Question

anonymous · Answer

(a) I think 12
3478,3748,4378,4738,7438,7348
Same for numbers ending with 4

chriss · Answer

b should be 4*4*4*2 or 128

and I come up with the same answer for a as abdul - 3*2*1 for each configuration ending in 4 or 8

anonymous · Answer

chrisS may you explain how you got a) thx

chriss · Answer

Ok so there are 2 numbers you can end with and be even, 4 or 8, so you need to set up two scenarios with each ending.  In either case, you are left with three numbers to work with and since there is no repetition, you have 3! and since you have 2 possible endings, you get 2(3!)

anonymous · Answer

oh i seee thank you very much
 =]

chriss · Answer

you're welcome :)

anonymous · Answer

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