SOLUTION: Suppose a certain traffic light shows a red light for 42 seconds, a green light for 45 seconds, and a yellow light for 5 seconds. If you look at this light at a randomly chosen

Question 1022861: Suppose a certain traffic light shows a red light for 42 seconds, a green light for 45 seconds, and a yellow light for 5 seconds.
If you look at this light at a randomly chosen instant, what is the probability that you see a red or yellow light? (Enter your probability as a fraction.)

Answer by robertb(5830) (Show Source): You can put this solution on YOUR website!
By the addition law, P(R or Y) = P(R) + P(Y) - P(R and Y).
But R and Y are mutually exclusive events, so P(R and Y) = 0.
==> P(R or Y) = P(R) + P(Y) = 42/92 + 5/92 = 47/92.
RELATED QUESTIONS
Suppose a certain traffic light shows a red light for 41 seconds, a green light for 45... (answered by Boreal)

Suppose a certain traffic light shows a red light for 45 seconds, a green light for 45... (answered by ikleyn)

The route from A to B passes two traffic light. at the first traffic light ,the red light (answered by Theo)

A traffic light is red for 25 seconds, yellow for 5 seconds and green for 55 seconds.... (answered by Theo)

A traffic light is red for 25 seconds, yellow for 5 seconds, and green for 55 seconds.... (answered by kingme18)

*Traffic light math question At a traffic light, one cycle through green-yellow-red... (answered by ikleyn)

A traffic light flashes red for 50 seconds, yellow for 5 seconds, and green for 65... (answered by stanbon)

At a traffic light, one cycle through green-yellow-red lasts for 110 seconds. The green... (answered by checkley77)

A traffic light is green for 50 seconds yellow for 10 seconds and red for 40 seconds (answered by stanbon)