Problem of the Week
Problem E
Spinning Red

A spinner is divided into $15$ equal sections. Each section is coloured either red or yellow. An arrow is attached to the centre of the spinner. Jamal spins the arrow two times. If there is a $64\mathrm{\%}$ chance of landing on red in at least one of the two spins, how many red sections are there?

Note: You may use the following fact from probability theory: If the probability of event $A$ occurring is $a$, the probability of event $B$ occurring is $b$, and the events are not dependent on each other, then the probability of both events occurring is $a\times b.$