A spinner is divided into four sectors with central angles 60°, 90°, 120° and 90°, coloured red, blue, green and yellow respectively. The pointer is spun once and is equally likely to stop anywhere. What is the probability that it stops on green or blue?

The four sectors are not equal, so the probability of a colour is its angle out of 360°. Green and blue together cover 120° + 90° = 210°, giving 210/360 = 7/12. Counting two of the four sectors as if the sectors were equally likely gives 1/2, and 5/12 is the probability of the remaining red-or-yellow region (150° out of 360°).