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1) Write down the steps of a hypothesis testing for the research question: “Whet

ID: 2958658 • Letter: 1

Question

1) Write down the steps of a hypothesis testing for the research question: “Whether the mean body-weight in this population is 150 lb?” Use SPSS to obtain the value of the test statistic and p-value.

2) Use SPSS to calculate a 90%, a 95% and a 99% CI for the true mean body-weight in this population. How do you interpret the findings?

192.00
152.00
135.00
110.00
128.00
180.00
260.00
170.00
165.00
150.00
110.00
120.00
185.00
165.00
212.00
119.00
165.00
210.00
186.00
100.00
195.00
170.00
120.00
185.00
175.00
203.00
185.00
123.00
139.00
106.00
180.00
130.00
155.00
220.00
140.00
157.00
150.00
172.00
175.00
133.00
170.00
130.00
101.00
180.00
187.00
148.00
106.00
180.00
127.00
124.00
215.00
125.00
194.00

Explanation / Answer

Given n=53, xbar=mean=158.75, s=35.65

(1) The test hypothesis is
Ho:=150
Ha: not equal 150

The test statistic is

Z=(xbar-)/(s/n)

=(158.75-150)/(35.65/sqrt(53))

=1.79

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(2)Given =0.1, |Z(0.05)|=1.645 (check normal table)

So the 90% CI for the mean is

xbar ± Z*s/n

--> 158.75 ± 1.645*35.65/sqrt(53)

--> (150.6946, 166.8054)

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Given =0.05, |Z(0.025)|=1.96 (check normal table)

So the 95% CI for the mean is

xbar ± Z*s/n

--> 158.75 ± 1.96*35.65/sqrt(53)

--> (149.1521, 168.3479)

----------------------------------------------------------------------------------

Given =0.01, |Z(0.005)|=2.58 (check normal table)

So the 99% CI for the mean is

xbar ± Z*s/n

--> 158.75 ± 2.58*35.65/sqrt(53)

--> (146.116, 171.384)