Consider this scenario: A traffic signal for eastbound traffic is red for 15 seconds, yellow for 5 seconds, and green for 30 seconds. The traffic policemen want to know the probability that out of the next x number of eastbound cars that arrive at that signal (where x>3), 3 of them would be stopped by a red light. What is the probability that out of the next 8 eastbound cars that arrive at the signal, exactly 3 will be stopped by a red light? 0.254 0.552 0.806 0.448

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22 October, 16:13

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Amy Mccann · Answer 1

P (3 reds out of 8)

= 8C3 * [15 / (15 + 5 + 30) ]^3 * [ (5 + 30) / (15 + 5 + 30) ]^ (8 - 3)

= 8C3 * 0.3^3 * 0.7^5

= 0.25412184

= 25.4%

=~ 0.3