# Probability of Traffic Signals

A box contains glass lenses used for traffic signals. Six are red, four are yellow, and seven are green. If two are chosen at random find the probability they are both green, if:

a. the first lense is replaced before the second is chosen

b. the first lense is not replaced before the second is chosen.

https://brainmass.com/statistics/probability/probability-traffic-signals-15625

#### Solution Preview

Total number of lenses = 6+4+7 = 17

<br>a. When the first lens is chosen, the probability of it being green =

<br>7/17. Now the lens is put back in ...

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