Math Prob/solving
posted by Lisa on .
As Frank drives to work he has to pass through three lights. The probability that any light is green is 39%. Estimate the probability that exactly two lights will be green. Use the following list of digits which was taken from a table of random numbers. In each pair of digits, let 0038 represent a green light and let the digits 3999 represent a light that is not green. Start at the top left of the table and move all the way across to the right of the table before moving down to the next row.
A)7/25 B) 5/25
C)6/25 D)4/25

You have not provided the random number table, but a combinatorial formula can be used for the exact probability
P = (0.39)^2*(0.61)*[3!/2!) = 0.27834 = 6.96/25
Answer A is closest. 
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