To investigate the effect of price on toaster sales, a chain of department stores decided to raise the price of a certain brand of toaster in 20 randomly selected stores (Sample A) and to lower the price in 10 randomly selected stores (Sample B). Monthly revenue (number sales x sales price) from these toasters was recorded for each of the 30 stores. Results from the two samples are as follows: No. of stores Sample A Sample B Mean $842 $817 Std. Dev. $217 $202 20 10 If you considered these to be independent samples, what would be the pooled estimate of the standard deviation for revenue? Calculate a 95% confidence interval for the difference between (a) (b) the two means.

MATLAB: An Introduction with Applications
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Author:Amos Gilat
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To investigate the effect of price on toaster sales, a chain of department
stores decided to raise the price of a certain brand of toaster in 20
randomly selected stores (Sample A) and to lower the price in 10
randomly selected stores (Sample B). Monthly revenue (number sales x
sales price) from these toasters was recorded for each of the 30 stores.
Results from the two samples are as follows:
No. of stores
Sample A
Sample B
Mean
$842
$817
Std. Dev.
$217
$202
20
10
If you considered these to be independent samples, what would
be the pooled estimate of the standard deviation for revenue?
Calculate a 95% confidence interval for the difference between
(a)
(b)
the two means.
Transcribed Image Text:To investigate the effect of price on toaster sales, a chain of department stores decided to raise the price of a certain brand of toaster in 20 randomly selected stores (Sample A) and to lower the price in 10 randomly selected stores (Sample B). Monthly revenue (number sales x sales price) from these toasters was recorded for each of the 30 stores. Results from the two samples are as follows: No. of stores Sample A Sample B Mean $842 $817 Std. Dev. $217 $202 20 10 If you considered these to be independent samples, what would be the pooled estimate of the standard deviation for revenue? Calculate a 95% confidence interval for the difference between (a) (b) the two means.
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