Question

5. For the past 10 days, a city planner has counted the number of

northbound cars that pass through a particular intersection During
that time, 200 or more cars were counted 9 out of 10 days.

a. What is the experimental probability that there will be 200 or more
northbound cars passing through the intersection on the eleventh day?

b. What is the experimental probability that there will not be 200 or
more northbound cars passing through the intersection on the
eleventh day?


Can someone please help I’m stuck ( and please show the work) thank you.

Answer 1

Event=200 or more cars

The number of cars was counted on 10 days and thus there were 10 trials.

# of trials=10

200 or more cars were counted on 9 of the 10 days and thus the event occurs 9 times.

# of times the event occurs= 9

The probability is the number of times the event occurs divided by the number of trials:

P ( 200 or more cars)= # of times the event occurs / # of trials

=9/10
0.9
90%

We know that the sum Of the probabilities Of an event And it’s Complement needs to be equal to 1.

P( event ) + P ( complement)= 1

What is it is “200 or more cars”

P( 200 or more cars) + P (not 200 or more cars) = 1

Since P ( 200 or more cars) = 9/10 we can replace P ( 200 or more cars) in the equation by 9/10

9/10 +P ( not 200 or more cars) =1

Subtract 9/10 from each side

-9/10= 1-9/10

Combine like terms

P( not 200 or more cars) = 1/10= 0.1 = 10%

A: 9/10 = 0.9 = 90%
B: 1/10= 0.1= 10%