The heart rate of 20 randomly selected adults was on average 85 beats per minute (bpm) with a standard deviation of 5 bpm. Build a 95% confidence interval for the mean heart rate of adults in the population. Interpret the interval you have created.

(82.66, 87.34).

Step-by-step explanation:

When population standard deviation is unknown and sample size is small , then the formula is used to find the confidence interval for is given by :-

, where n = sample size , = sample mean , t*= two tailed critical value s= sample population standard deviation, .

Given, , s=5, n=20 , degree of freedom = 19  [∵df=n-1]

For 95% confidence level ,

By t-distribution table ,

t-value for   (two tailed) and df =19 is t*=2.0930

Now , the 95% confidence interval for the mean heart rate of adults in the population will be :

Hence, the required interval is (82.66, 87.34).

Interpretation : A person can be 95% confident that the mean heart rate of adults in the population lies between (82.66, 87.34).

c.

step-by-step explanation:

because first you have to add the 4x, 9x, and the 7x together and you get 20x and then you add the last numbers up and you get 5and then you put the subtraction sign in there and that's how you get the answer.