What is the probability that a two digit number chosen at random will be a multiple of 3 and not of 5 .

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- Jan 18th 2009, 11:57 PMmathaddictnumbers + probability
What is the probability that a two digit number chosen at random will be a multiple of 3 and not of 5 .

- Jan 19th 2009, 12:19 AMmr fantastic
- Jan 20th 2009, 11:20 AMSoroban
Hello, mathaddict!

Quote:

What is the probability that a two digit-number chosen at random

will be a multiple of 3 and not of 5?

There are 90 two-digit numbers.

One-third of them are mutliples of 3: . multiples of 3.

But every fifth one of them is a multiple of 5: . multiples of 15.

Hence, there are: . multiples of 3 which are not multiples of 5.

Therefore: .