asap please # 2 Elementary Statistics Departmental Final Exam PartI (Form A) Emp

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asap please # 2

Elementary Statistics Departmental Final Exam PartI (Form A) EmplID Problem #2(12 points) -+r rnst of Living and Rent Cost Index fnr "… Elementary Statistics Departmental Final Exam EmplID Part Il (Form A) Problem #2 (12 points) An automobile manufacturer introduces a new model that averages 2d city under normal conditions. Assume that in-city mileage for t normally distributed with standard deviation of 2.5 miles per gallon. is approximately this model is approximately What is the probability that a person who will purchase car that averages between 25 and 29 miles per gallon for in this model, will end up with a (5 points) a. -city driving? b. Find the value of the 90th percentile, Pso, for this random variable. (S points) Use information from part (b) to circle the correct choice and to fill in the blanks in the following sentence: c. (2 points) % of the new model cars average (at least/at mos t)miles per gallon for in-city driving. Show your work. Partial credit will be given

Explanation / Answer

2)a) P(25 < x < 29)

= P((25 - mean)/SD < (x - mean)/SD < (29 - mean)/SD)

= P((25 - 27)/2.5 < Z < (29 - 27)/2.5)

= P(-0.8 < Z < 0.8)

= P(Z < 0.8) - P(Z < -0.8)

= 0.7881 - 0.2119 = 0.5762

B) P(X < x) = 0.9

Or, P((X - mean)/SD < (x - mean)/SD) = 0.9

Or, P(Z < (x - 27)/2.5) = 0.9

Or, (x - 27)/2.5 = 1.28

Or, x = 1.28 * 2.5 + 27

Or, x = 30.2

C)90% of the new model cars average 30.2 miles per gallon for in - city - driving.

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