Probability that a 3-digit randomly chosen number is divisible by 5

Question

$$\text{Set}\; = \{0,1,2,3,4,5,6\}$$

Find the probability that a three digit number which does not have the digit $0$ chosen at the far left and is chosen at random from the set, is NOT a multiple of 5.

$$P(\text{NOT A multiple of 5}) = \dfrac{6\cdot 7 \cdot 5}{6\cdot 7\cdot 7} = \dfrac{210}{294} = \frac{5}{7}$$

Is this correct?

Yes, this is just fine. – Brian M. Scott Jul 05 '13 at 19:15 — Brian M. Scott, Jul 05 '13 at 19:15
IF you sample with replacement, yes – Alex Jul 05 '13 at 19:58 — Alex, Jul 05 '13 at 19:58

amWhy · Answer 1 · 2013-07-18T23:00:09.347

4

It is perfectly correct, yes. Well done.

But in any "submitted" answer you might give, e.g., in an assignment or on a test, it would also be good to include a few words about how you arrived at your answer, or why you believe it is the answer. Oftentimes, the calculations "speak for themselves," and the reasoning is easily followed, but not always.

edited Jul 18 '13 at 23:00

answered Jul 05 '13 at 19:30

amWhy

209,954

MethodMan: any chance you might be thinking of accepting this answer? ;-) – amWhy Jul 18 '13 at 23:30

Probability that a 3-digit randomly chosen number is divisible by 5

1 Answers1