Question

Find the probability for the experiment of tossing a six-sided die twice. Put the answer in a/b form.

P(the sum is odd or prime)

Answer 1

I suggest you make a table of sums for 6 rows and 6 columns from the numbers from 1 to 6
Fill in the sums, e.g. the first row and last row would be
2 3 4 5 6 7
....
7 8 9 10 11 12

count up all the odd ones, obviously 18 of them
Remember 2 is a prime number so it must be included as well
All other primes would be odd, and are already counted.
so prob(of your event) = 19/36