# Connexions

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Textbook by: Kathy Chu, Ph.D.. E-mail the author

# Review

Module by: Kathy Chu, Ph.D.. E-mail the author

The next three questions refer to the following information: Richard’s Furniture Company delivers furniture from 10 A.M. to 2 P.M. continuously and uniformly. We are interested in how long (in hours) past the 10 A.M. start time that individuals wait for their delivery.

## Exercise 1

X X size 12{X "~" } {} ~

• A. U ( 0,4 ) U ( 0,4 ) size 12{U $$0,4$$ } {}
• B. U ( 10 , 2 ) U ( 10 , 2 ) size 12{U $$"10",2$$ } {}
• C. N ( 2,1 ) N ( 2,1 ) size 12{N $$2,1$$ } {}

A

## Exercise 2

The average wait time is:

• A. 1 hour
• B. 2 hour
• C. 2.5 hour
• D. 4 hour

B

## Exercise 3

• 40% of full-time students took 4 years to graduate
• 30% of full-time students took 5 years to graduate
• 20% of full-time students took 6 years to graduate
• 10% of full-time students took 7 years to graduate

The expected time for full-time students to graduate is:

• A. 4 years
• B. 4.5 years
• C. 5 years
• D. 5.5 years

C

## Exercise 4

The length of time to brush one’s teeth is generally thought to be exponentially distributed with a mean of 3 4 3 4 size 12{ { {3} over {4} } } {} minutes. Find the probability that a randomly selected person brushes his/her teeth less than 3 4 3 4 size 12{ { {3} over {4} } } {} minutes.

• A. 0.5
• B. 3 4 3 4 size 12{ { {3} over {4} } } {}
• C. 0.43
• D. 0.63

D

## Exercise 5

Which distribution accurately describes the following situation?

The chance that a teenage boy regularly gives his mother a kiss goodnight (and he should!!) is about 20%. Fourteen teenage boys are randomly surveyed.

X=X= size 12{X={}} {}the number of teenage boys that regularly give their mother a kiss goodnight

• A. B ( 14 , 0 . 20 ) B ( 14 , 0 . 20 ) size 12{B $$"14",0 "." "20"$$ } {}
• B. N ( 2 . 8,2 . 24 ) N ( 2 . 8,2 . 24 ) size 12{N $$2 "." 8,2 "." "24"$$ } {}

A

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