6 of 9 KFUPM STAT319 ID: Department of MATH &STAT; NAME: Chapter 7 &4: 1. The am

Question

6 of 9 KFUPM STAT319 ID: Department of MATH &STAT; NAME: Chapter 7 &4: 1. The amount of time it takes a student to walk from her home to class has a skewed right distribution with a mean of 14 minutes and a standard deviation of 1 minutes. If data were collected from 40 randomly selected walks, describe the sampling distribution of , the sample mean time. Answer 2. The owner of a computer repair shop has determined that their daily revenue has mean $7200 and standard deviation $1200. The daily revenue totals for the next 30 days will be monitored. What is the probability that the mean daily revenue for the next 30 days will exceed $7500 Answer

Explanation / Answer

Solution1:

mean of sampling distribution of x bar=unbiased estimation of population mean(mu)

there is no tendency for a sample average to fall systematically above or below mu,even if thw population distribution is skewed .

x bar is an unbiased estimator of the population mu asuming samples are randomly chosen.

=14 minutes'

ANSWER: 14 MINUTES

Solution2:

mean=7200

sd=1200

n=30

P(X bar>7500)

convrt to z

z=x-mean/sd/sqrt(n)

=7500-7200/1200/sqrt(30)

=300/1200/sqrt(30)

Z=1.3

P(Z>1.37 ) to be found

=1-P(Z<1.37)

=1-0.9147

=0.0853

ANSWER :0.0853

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