In a sample of 8 high school students, they spent an average of 28.8 hours each week doing sports with a sample standard deviation of 3.2 hours. find the 95% confidence interval, assuming the times are normally distributed.

Step-by-step explanation:

Since the population standard deviation is unknown, and the sample standard deviation , must replace it, the distribution  must be used for the confidence interval.

The sample size is n=8.

The degree of freedom is , .

With 95% confidence level, the (significance level) is 5%.

Hence with 7 degrees of freedom, . (Read from the t-distribution table see attachment)

The 95% confidence interval can be found by using the formula:

.

The sample mean is hours.

The sample sample standard deviation is hours.

We now substitute all these values into the formula to obtain:

.

We are 95% confident that the population mean is between 26.12 and 31.48  hours.

the multiples of 15 are 15, 30,45, 60, 75, 90, 105, 120, 135, 150, 165, 180, 195,   210, 225, 240, 255, 270, 285, 300, 315, 330, 345, 360, 375,   390, 405, 420, 435, 450, 465, 480, 495, 510, 525, 540, 555, 570, 585, 600, 615, 630, 645, 660, 675, 690, 705, 720, and 735.

the factors of 15 are 1, 3, 5, and 15.

hope that , fam!

-une, your fren : )