Posted by **failureinmath** on Thursday, November 15, 2012 at 10:36am.

What is the probability that a randomly selected divisor of 720 is a multiple of 4? Express your answer as a common fraction.

- PLEASE HELP - DIVISORS PROB -
**Steve**, Thursday, November 15, 2012 at 12:03pm
since 720 = 4*180

and 180 = 2^2 3^2 5

180 has 18 factors:

1 2 4 6 12 18 36

10 20 30 60 90

3 9 15 45 180

I'd say 1/18, since all the factors that are multiples of 4 will be 4 times one of the factors in the list.

- PLEASE HELP - DIVISORS PROB -
**geometrygeeeeek**, Friday, November 16, 2012 at 11:26am
thanks alot

- PLEASE HELP - DIVISORS PROB -
**Jacob**, Sunday, January 20, 2013 at 12:28pm
3/5

- PLEASE HELP - DIVISORS PROB -
**s**, Saturday, October 18, 2014 at 8:41pm
15

- PLEASE HELP - DIVISORS PROB -
**Someone**, Wednesday, August 5, 2015 at 8:50pm
Using the above logic, the answer is 3/5.

All the reasoning is correct (About the factors of 180). The only problem is that the probability of selecting one. Since the prime factorization of 720 is 2^4 x 3^2 x 5, then the number of factors that 720 has is (4+1)(2+1)(1+1)=30. So, the answer is 18/30=3/5

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