On the island of Timbuktoo the probability that a set of traffic lights shows red, yellow or green is equally likely. Christa is travelling down a road where there are two sets of traffic lights.
What is the probability that both sets of traffic lights will be red?
Three fair coins are tossed.
A bucket contains $5$5 green buttons and $7$7 purple buttons. Two buttons are drawn in succession from the bucket. The first button is replaced before the second button is drawn.
Han plays three tennis matches. In each match he has $60%$60% chance of winning: