A random sample of 18 fields of barley has a mean yield of 36.4 bushels per acre and standard deviation of 7.37 bushels per acre. Determine the 80% confidence interval for the true mean yield. Assume the population is approximately normal.

So, the confidence interval is [34.08, 38.72].

Step-by-step explanation:

We know that a  random sample of 18 fields of barley has a mean yield of 36.4 bushels per acre and standard deviation of 7.37 bushels per acre.  

We have :

We use the Appendix: Critical Values Tables, and we get that:

We calculate the margin of error:

We get the boundaries of the confidence interval:

So, the confidence interval is [34.08, 38.72].

b. 1.25 hr

step-by-step explanation:

if you have a constant speed of 60 mph, then you have a ratio between 60 mi. to 1 hr. dividing both sides by 60 we get the ratio

1 mi. to

then mult. both sides by 75 we get the ratio

75 mi. to

simplifying we get

75 mi. to

or 1.25 hr.

0.038

step-by-step explanation: