Total = 55 + 5 + 20 = 80
P( green) + P( yellow) - P(green and yellow)
( 55 + 5)/80 -0
P = 60/80 = .75
P( green) + P( yellow) - P(green and yellow)
( 55 + 5)/80 -0
P = 60/80 = .75
The total time for one full cycle is the sum of the times for green, yellow, and red:
Total time = green time + yellow time + red time = 55 + 5 + 20 = 80 seconds.
The total time for green or yellow is the sum of the times for green and yellow:
Green or yellow time = green time + yellow time = 55 + 5 = 60 seconds.
Finally, we can calculate the probability as the ratio of the time for green or yellow to the total time:
Probability = (Green or yellow time) / (Total time) = 60 / 80 = 0.75.
Therefore, the probability that the driver approaching this traffic light will find it green or yellow is 0.75 or 75%.
The total time for one complete cycle of the traffic light can be calculated by summing the durations of each color: 55 seconds (green) + 5 seconds (yellow) + 20 seconds (red) = 80 seconds.
The total time that the light is green or yellow is the sum of the durations of the green and yellow lights: 55 seconds (green) + 5 seconds (yellow) = 60 seconds.
Now, we can calculate the probability by dividing the total time that the light is green or yellow by the total time for one complete cycle:
Probability = (Time for green or yellow) / (Total time for one complete cycle) = 60 seconds / 80 seconds = 0.75
Therefore, the probability that the driver approaching this traffic light will find it green or yellow is 0.75, or 75%.