Police estimate that 84% of drivers wear their seatbelts. they set up a safety roadblock, stopping cars to check for seatbelt use. if they stop 140 cars,
what is the probability they find at least 27 drivers not wearing their seatbelts?
use a normal approximation.

0.8802

Step-by-step explanation:

given that the Police estimate that 84% of drivers wear their seatbelts.

when they stop 140 cars, no of trials = no of cars checked = 140

Each car is independent of the other

Hence X no of cars with drivers wearing seat belts is binomial with p = 0.85

Required probability =

the probability they find at least 27 drivers not wearing their seatbelts

Since normal approximation is required we can approximate to

X is Normal with mean = np =

std dev =

Required probability =atelast 27 drivers not wearing their seatbelts

= P(X>(140-27))

= P(X>113)

5+2x=a

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