Mary has $15 and she wants to buy some earrings. She picks one pair that costs $7.99 and two pairs that cost $2.59 each. Which s
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Answer:
And the 95% confidence interval for the difference in the means is given by:
Step-by-step explanation:
Previous concepts
A confidence interval is "a range of values that’s likely to include a population value with a certain degree of confidence. It is often expressed a % whereby a population means lies between an upper and lower interval".
The margin of error is the range of values below and above the sample statistic in a confidence interval.
Normal distribution, is a "probability distribution that is symmetric about the mean, showing that data near the mean are more frequent in occurrence than data far from the mean".
sample mean for inhibitor A
sample standard deviation for inhibitor A
sample size for A
sample mean for inhibitor B
sample standard deviation for inhibitor B
sample size for A
Solution to the problem
For this case the confidence interval for the difference of means is given by:
The degrees of freedom are given by:
Since the Confidence is 0.95 or 95%, the value of and
, and we can use excel, a calculator or a table to find the critical value. The excel command would be: "=-T.INV(0.025,87)".And we see that
And replacing we got:
And the 95% confidence interval for the difference in the means is given by: