a shopper purchase 8 t-shirts and 5 pairs of pants for $220 the next day he purchased 5T shirts and one pair of pants for $112 h
2 answers:
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Answer:
The margin of error of u is of 3.8.
The 99% confidence interval for the population mean u is between 27.4 minutes and 35 minutes.
Step-by-step explanation:
We have the standard deviation for the sample, which means that the t-distribution is used to solve this question.
The first step to solve this problem is finding how many degrees of freedom, we have. This is the sample size subtracted by 1. So
df = 28 - 1 = 27
99% confidence interval
Now, we have to find a value of T, which is found looking at the t table, with 27 degrees of freedom(y-axis) and a confidence level of . So we have T = 2.7707
The margin of error is:
In which s is the standard deviation of the sample and n is the size of the sample.
The margin of error of u is of 3.8.
The lower end of the interval is the sample mean subtracted by M. So it is 31.2 - 3.8 = 27.4 minutes
The upper end of the interval is the sample mean added to M. So it is 31.2 + 3.8 = 35 minutes
The 99% confidence interval for the population mean u is between 27.4 minutes and 35 minutes.
ANSWER
The percentage decrease is 10.4%.
EXPLANATION
To calculate percentage decrease, use the formula,
Percentage decrease
Yesterday the price of coffee was 2.40. This is the old price.
Today the price is 2.15. This is the new price.
To the nearest tenth, we have:
Therefore the percentage decrease is 10.4%.
The percentage decrease is 10.4%.
EXPLANATION
To calculate percentage decrease, use the formula,
Percentage decrease
Yesterday the price of coffee was 2.40. This is the old price.
Today the price is 2.15. This is the new price.
To the nearest tenth, we have:
Therefore the percentage decrease is 10.4%.