Complete question :
Between 12:00 PM and 1:00 PM, cars arrive at Citibank’s drive-thru at the rate of 6 cars per hour (0.1 car per minute). The following formula from statistics can be used to determine the probability that a car will arrive within t minutes of 12:00 PM. F(t)=1−e^−0.1t
Determine how many minutes are needed for the probability to reach 80%.
Answer:
16.09 minutes
Explanation:
Given the function :
F(t)=1−e^−0.1t
To attain 80% probability ; 80% = 0.8
0.8 = 1 - e^-0.1t
0.8 - 1 = - e^-0.1t
-0.2 = - e^-0.1t
Take the In of both sides
In(0.2) = In( e^-0.1t)
−1.609437 = - 0.1t
Divide both sides by - 0.1
−1.609437 / -0.1 = - 0.1t / 0.1
16.09 = t
Hence, the time it'll take will be 16.09 minutes