Aresearcher wants to know if the average time in jail for robbery has increased from what it was several years ago when the average sentence was 7 years. he obtains data on 400 more recent robberies and finds an average time served of 7.5 years. if we assume the standard deviation is 3 years, a 95% confidence interval for the average time served is:

The interval is : (7.206 , 7.794)

Step-by-step explanation:

The mean is = 7.5

Standard deviation = 3

n = 400

At 95% confidence interval, the z score is 1.96

And

and

So, the interval is : (7.206 , 7.794)

these sign is used to tell weather the number is greater or less than the number   <   or >     but this sign means its equal =    

hope this you and

step-by-step explanation: