it has been reported that 25% of all cars on the highway are traveling at speeds in excess of 70mph. If the speeds of 7 random automobiles are measured via radar:

A-what is the probability thay exactly 3 cars are speeding?

B-prob at least one go 70

The probability that a car is speeding p = 25 % = 1/4. q = 1 - p = 3/4.

A . P(3 cars are speeding) = (7 C 3)*p^3*q^4 = 35*(1/4)^3 *(3/4)^4 = (35*81)/(64*256) = 2835/16384 = 0.1730

B. P(at least one car goes not faster than 70 mph) = 1 - 0.1730 = 0.8270

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