6.6 The “on” temperature of a thermostatically controlled switch for an air conditioning system is set at 60°F, but the actual temperature X at which the switch turns on is a random variable having probability density function a Find the probability that it takes a temperature in excess of 60°F to turn the switch on.

b If two such switches are used independently, find the probability that both require a temperature in excess of 60°F to turn on.