waiting times to receive food after placing an order at the local subway sandwich shop follow an exponential distribution with a mean of 60 seconds. calculate the probability a customer waits: a. less than 30 seconds. (round your answer to 4 decimal places.) b. more than 120 seconds. (round your answer to 4 decimal places.) c. between 45 and 75 seconds. (round your answer to 4 decimal places.)

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Respuesta :

Waiting time follows an exponential distribution with mean

μ=60

μ=60 seconds. This implies λ=1μ=160λ= μ1= 601

Let X be the waiting time. for first we have to calculate the probability of customers who wait less than 30 secs.

a. X is less than 30 seconds, then we have to find ,

P(X<X1)=1āˆ’eāˆ’Ī»X1⇒P(X<30)=1āˆ’eāˆ’Ī»Ć—0

=1āˆ’eāˆ’160Ɨ30 =1āˆ’eāˆ’12=1āˆ’0.6065

=0.3935P(X<X 1)⇒

P(X<30)

​

Ā 

=1āˆ’e āˆ’Ī»X 1=

1āˆ’e āˆ’Ī»Ć—30 1āˆ’e āˆ’ 601Ɨ30 =

1āˆ’e āˆ’ 21

=1āˆ’0.6065

=0.3935

​b. X is more than 120 seconds, then we have to find less than 120 sec

b. X is more than 120 seconds

P(X>X1)=1āˆ’P(X<X1)=1āˆ’(1āˆ’eāˆ’Ī»X1)⇒P(X>120)=1āˆ’(1āˆ’eāˆ’Ī»Ć—120=eāˆ’60Ɨ120=eāˆ’2=0.135

P(X>X 1)⇒P(X>120)=1āˆ’P(X<X 1)=1āˆ’(1āˆ’e āˆ’Ī»X 1)=1āˆ’(1āˆ’e āˆ’Ī»Ć—120= āˆ’ 601Ɨ120 =e āˆ’2=0.135

To learn more about probability.

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