Using the z-distribution, we have that:
- For a 99% confidence level, a sample size of 127 is needed.
- For a 95% confidence level, a sample size of 74 is needed, meaning that a decrease in the confidence level decreases the needed sample size, as M and n are inverse proportional.
<h3>What is a z-distribution confidence interval?</h3>
The confidence interval is:
The margin of error is:
In which:
- is the sample mean.
- is the standard deviation for the population.
For a 99% confidence interval, , hence z is the value of Z that has a p-value of , so the critical value is z = 2.575.
The margin of error and population standard deviation are:
Hence we have to solve for n to find the needed sample size, as follows:
n = 126.4.
Rounding up, for a 99% confidence level, a sample size of 127 is needed.
For the 95% confidence interval, we have that z = 1.96, hence:
n = 73.3.
Rounding up, for a 95% confidence level, a sample size of 74 is needed, meaning that a decrease in the confidence level decreases the needed sample size, as M and n are inverse proportional.
More can be learned about the z-distribution at brainly.com/question/25890103
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Step-by-step explanation:
Gradient of a line is (x-1-x2)+(y1-y2)
(2--2) +(-2--6)
(4)+(4)
(8)
the gradient of the line is 8
Answer:
$61.25
Step-by-step explanation:
The quantity for a 60-day supply is 60 times the 1-day usage. The BOGO offer means the sale price is effectively half the usual price.
__
One day supply: 2/3 can + 1/2 can = (4/6 +3/6) = 7/6 can
60-day supply: 60 × 7/6 can = 70 cans
Susan will be paying for 70/2 = 35 cans of dog food. (She will get 35 cans free.) So, her cost will be ...
35 × $1.75 = $61.25
The cost of Susan's dog food purchase would be $61.25 before tax.
Answer:
1.6 hours
Step-by-step explanation: