Question

In a study, 45 smokers were questioned about the number of hours they sleep each day. For the sample of smokers, the mean number of hours slept per day was 7.4 hours and the standard deviation was 1 hours. We wish to test the hypothesis that smokers have a different amount of sleep than the general public, who sleep for an average of 7.5 hours per day. Use ( alpha=0.05 ). a) Which one of the following is the appropriate pair of hypotheses? [ egin{array}{ll} H_{0}: mu=7.5 ; & H_{A}: mu eq 7.5 \ H_{0}: mu=7.4 ; & H_{A}: mu=7.5 \ H_{0}: mu=7.4 ; & H_{A}: mu eq 7.4 \ H_{0}: ar{x}=7.5 ; & H_{A}: ar{x} eq 7.5 \ H_{0}: ar{x}=7.4 ; & H_{A}: ar{x} eq 7.4 end{array} ] b) Calculate the standardized test statistic for this study. ( 3 mathrm{DP} ) c) Find the ( p )-value associated with the test statistic. d) From the ( p )-value you found above, select the appropriate conclusion for an hypothesis test carried out at the ( alpha=5 % ) significance level: As the ( p )-value is greater than or equal to 0.05 , there is no evidence at the 0.05 -significance level to reject ( H_{0} ) : i.e. there is no evidence that smokers sleep more or less than the general population. The observed difference is within the range we would expect due to random variation. As the ( p )-value is less than 0.05 , there is no evidence at the 0.05 -significance level to reject ( H_{0} ). The observed difference is within the range we would expect due to random variation. As the ( p )-value is less than 0.05 , we have evidence at the 0.05 -significance level that the true amount of sleep in the general population is more than 7.5 hours per night. As the ( p )-value is less than 0.05 , there is evidence to reject ( H_{0} ) at the 0.05 -significance level, which suggests that the true mean hours of sleep for smokers is different from the general population. We have evidence that ( 7.4 % ) of smokers sleep more than the general public.

          In a study, 45 smokers were questioned about the number of hours they sleep each day. For the sample of smokers, the mean number of hours slept per day was 7.4 hours and the standard deviation was 1 hours.
We wish to test the hypothesis that smokers have a different amount of sleep than the general public, who sleep for an average of 7.5 hours per day. Use ( alpha=0.05 ).
a) Which one of the following is the appropriate pair of hypotheses?
[
egin{array}{ll}
H_{0}: mu=7.5 ; & H_{A}: mu 
eq 7.5 \
H_{0}: mu=7.4 ; & H_{A}: mu=7.5 \
H_{0}: mu=7.4 ; & H_{A}: mu 
eq 7.4 \
H_{0}: ar{x}=7.5 ; & H_{A}: ar{x} 
eq 7.5 \
H_{0}: ar{x}=7.4 ; & H_{A}: ar{x} 
eq 7.4
end{array}
]
b) Calculate the standardized test statistic for this study.
( 3 mathrm{DP} )
c) Find the ( p )-value associated with the test statistic.
d) From the ( p )-value you found above, select the appropriate conclusion for an hypothesis test carried out at the ( alpha=5 % ) significance level:
As the ( p )-value is greater than or equal to 0.05 , there is no evidence at the 0.05 -significance level to reject ( H_{0} ) : i.e. there is no evidence that smokers sleep more or less than the general population. The observed difference is within the range we would expect due to random variation.
As the ( p )-value is less than 0.05 , there is no evidence at the 0.05 -significance level to reject ( H_{0} ). The observed difference is within the range we would expect due to random variation.
As the ( p )-value is less than 0.05 , we have evidence at the 0.05 -significance level that the true amount of sleep in the general population is more than 7.5 hours per night.
As the ( p )-value is less than 0.05 , there is evidence to reject ( H_{0} ) at the 0.05 -significance level, which suggests that the true mean hours of sleep for smokers is different from the general population.
We have evidence that ( 7.4 % ) of smokers sleep more than the general public.
        
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In a study, 45 smokers were questioned about the number of hours they sleep each day. For the sample of smokers, the mean number of hours slept per day was 7.4 hours and the standard deviation was 1 hours.
We wish to test the hypothesis that smokers have a different amount of sleep than the general public, who sleep for an average of 7.5 hours per day. Use ( alpha=0.05 ).
a) Which one of the following is the appropriate pair of hypotheses?
[
eginarrayll
H0: mu=7.5 ;     HA: mu 
eq 7.5 H0: mu=7.4 ;     HA: mu=7.5 H0: mu=7.4 ;     HA: mu 
eq 7.4 H0: arx=7.5 ;     HA: arx 
eq 7.5 H0: arx=7.4 ;     HA: arx 
eq 7.4
endarray
]
b) Calculate the standardized test statistic for this study.
( 3 mathrmDP )
c) Find the ( p )-value associated with the test statistic.
d) From the ( p )-value you found above, select the appropriate conclusion for an hypothesis test carried out at the ( alpha=5 % ) significance level:
As the ( p )-value is greater than or equal to 0.05 , there is no evidence at the 0.05 -significance level to reject ( H0 ) : i.e. there is no evidence that smokers sleep more or less than the general population. The observed difference is within the range we would expect due to random variation.
As the ( p )-value is less than 0.05 , there is no evidence at the 0.05 -significance level to reject ( H0 ). The observed difference is within the range we would expect due to random variation.
As the ( p )-value is less than 0.05 , we have evidence at the 0.05 -significance level that the true amount of sleep in the general population is more than 7.5 hours per night.
As the ( p )-value is less than 0.05 , there is evidence to reject ( H0 ) at the 0.05 -significance level, which suggests that the true mean hours of sleep for smokers is different from the general population.
We have evidence that ( 7.4 % ) of smokers sleep more than the general public.

Added by Sina L.

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Elementary Statistics a Step by Step Approach
Elementary Statistics a Step by Step Approach
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Transcript

-
00:01 For this question, we want to test whether a population mean is different from 7 .5.
00:08 We're asked to test at a significance level of 0 .05.
00:12 To do so, we have a sample of 45, which yielded a sample mean of 7 .4, and a sample standard deviation of 1.
00:23 For this situation, the null hypothesis would be that the population mean is 7 .5, and the alternative hypothesis is that the mean is different from 7 .5.
00:41 Hypotheses are always about a population parameter.
00:47 Then we calculate the test statistic.
00:50 Since we don't know the population standard deviation, we must make use of the sample standard deviation.
00:56 Therefore, our test statistic is based on the t -distribution with n -1, or 44 degrees of freedom.
01:03 It's calculated as the sample mean minus the null hypothesized mean, divided by the sample standard deviation, over the square root of the sample size...
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