Posted by **HM** on Wednesday, November 2, 2011 at 1:25pm.

a spinner has regions numbered through 1-21

what is the probability that the spinner will stop on an even number or a multiple of 3..

I am confused.

I keep coming up with 17/21

but the real answer is 2/3

how how how ?

- PROBABILITY MATH -
**PsyDAG**, Wednesday, November 2, 2011 at 11:07pm
Even number = 10/21

Multiple of 3 = 7/21

10/21 + 7/21 = 17/21

Guess what? I keep coming up with 17/21 too.

Book typo?

- PROBABILITY MATH -
**Michael**, Saturday, November 17, 2012 at 10:06am
A= 16/21

You need to remember that 6 is also an even number, so you can't count it twice as it is only one number. So you have 10 possible even numbers, plus 7 possible numbers that are multiples of 3, minus 1 multiple of 3 (the number 6) because you already counted it in your even numbers.

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