Question

Older people often have a hard time finding work. AARP reported on the number of weeks it takes a worker aged 55 plus to find a job. The data on number of weeks spent searching for a job collected by AARP (AARP Bulletin, April 2008) Shows that the mean number of weeks a worker aged 55 plus spent to find a job is 22 weeks. The sample standard deviation is 11.89 weeks and sample size is 40.a) Provide a point estimate of the population mean number of weeks it takes a worker aged 55 plus to find a job.
b) At 95% confidence, what is the margin of error?
c) What is the 95% confidence interval estimate of the mean?
d) Discuss the degree of skewness found in the sample data. What suggestion would you make for a repeat of this study?

Answer 1

Answer:

Step-by-step explanation:

Hello!

Be the variable of interest:

X: Number of weeks it takes a worker aged 55 plus to find a job

Sample average X[bar]= 22 weeks

Sample standard deviation S= 11.89 weeks

Sample size n= 40

a)

The point estimate of the population mean is the sample mean

X[bar]= 22 weeks

It takes on average 22 weeks for a worker aged 55 plus to find a job.

b)

To estimate the population mean using a confidence interval, assuming the variable has a normal distribution is

X[bar] ± $t_{n_1; 1-\alpha /2}$ * $\frac{S}{\sqrt{n} }$

$t_{n-1; 1-\alpha /2}= t_{39; 0.975}= 2.023$

The structure of the interval is "point estimate" ± "margin of error"

d= $t_{n_1; 1-\alpha /2}$ * $\frac{S}{\sqrt{n} }$= 2.023*$(\frac{11.89}{\sqrt{40} })$= 3.803

c)

The interval can be calculated as:

[22  ±  3.803]

[18.197; 25.803]

Using s 95% confidence level, you'd expect the population mean of the time it takes a worker 55 plus to find a job will be within the interval [18.197; 25.803] weeks.

d)

Job Search Time (Weeks)

21 , 14, 51, 16, 17, 14, 16, 12, 48, 0, 27, 17, 32, 24, 12, 10, 52, 21, 26, 14, 13, 24, 19 , 28 , 26 , 26, 10, 21, 44, 36, 22, 39, 17, 17, 10, 19, 16, 22, 5, 22

To study the form of the distribution I've used the raw data to create a histogram of the distribution. See attachment.

As you can see in the histogram the distribution grows gradually and then it falls abruptly. The distribution is right skewed.