Question

How many 4 digit numbers can be formed using only the numbers 3 2 7 6 0 4 9 if:
a) there are no repeats allowed?
b) the number is odd and no repeats allowed?
c) the number is greater than 4000 and no repeats are allowed?
d) the number is greater than 4000 and repeats are allowed?

My answer to follow...last one, for now I think :D

Answer 1

a) 840
b) 360
c)480
d) 1371

Answer 2

arg..wait...this doesn't make sense. should it be 7c4 ?? and same for the rest

Answer 3

first one is 7 choose 4 so it can't be that large

Answer 4

do the rest use that method too ?

Answer 5

second is 3 choose 1 times 6 choose 3

Answer 6

the rest require too much thinking for me but the method is the same
last one is different actually because repeats are allowed

Answer 7

actually greater than 4000 just means starts with 4, 6, 7, or 9

Answer 8

I got that part but I'm pretty sure I've screwed up this entire assignment not using nCr....sigh back to the drawing board I guess. thank you!

Answer 9

on line class or do you have to hand this in?

Answer 10

btw don't use nCr for the last one, because you can repeat

Answer 11

online class.thought i'd be smart and get ahead in summer school...such a bad idea lol

Answer 12

it will be over soon enough, and then you will be done
besides, you can always get help here

Answer 13

first website I found that is actually useful..most you have to pay for or just don't help at all, this one is awesome

Answer 14

i think so too

Answer 15

thought this would be my last question..that was untrue..