Question

tossing a coin tails up or rolling a number less than 4 on a number cube.

I got 1/2 + 3/6 and got 1.
The answer is 3/4. I don't understand what to do. Please help.

Answer 1

clearly the answer cannot be 1, since that would mean you always get tails or roll less than 4.

there are 12 possible outcomes, easy to list them.

1/2 give tails
1/2 * 3/6 = 1/4 gives heads and n<4.

1/2 + 1/4 = 3/4

or, consider P(heads & n>=4) = 1/2 * 1/2 = 1/4

you want 1 minus that, or 3/4.