SOLUTION: a traiffic lights follows the pattern green (50 seconds), yell (5 seconds), and red (25 seconds). What is the probability that a driver approaching this light will find it green o

Algebra ->  Quadratic Equations and Parabolas  -> Quadratic Equations Lessons -> SOLUTION: a traiffic lights follows the pattern green (50 seconds), yell (5 seconds), and red (25 seconds). What is the probability that a driver approaching this light will find it green o      Log On


   



Question 30321: a traiffic lights follows the pattern green (50 seconds), yell (5 seconds), and red (25 seconds). What is the probability that a driver approaching this light will find it green or yellow?
Answer by Earlsdon(6294) About Me  (Show Source):
You can put this solution on YOUR website!
Let's see...the traffic lights are on (green, yellow, or red) for a total of 50 seconds (green) + 5 seconds (yellow) + 25 seconds (red) = 80 seconds.
So, the probability of a green light being on is:
p%28G%29+=+50%2F80
p%28G%29+=+5%2F8
The probability of a yellow light being on is:
p%28Y%29+=+5%2F80
p%28Y%29+=+1%2F16
The probability of a red light being on is:
p%28R%29+=+25%2F80
p%28R%29+=+5%2F16
The probability of A or B is:
p%28A+or+B%29+=+p%28A%29+%2B+p%28B%29+-+p%28A+and+B%29 but for mutually exclusive events such as in this situation (Only one of the lights can be on at any time), p%28A+and+B%29+=+0 so we have:
p%28A+or+B%29+=+p%28A%29+%2B+p%28B%29
For the traffic lights, the probability of green or yellow being on is:
p%28G+or+Y%29+=+p%28G%29+%2B+p%28Y%29
p%28G+or+Y%29+=+%285%2F8%29+%2B+%281%2F16%29
p%28G+or+Y%29+=+11%2F16