Aresearcher wants to know if the average time in jail for robbery has increased from what it was 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. find a 95% confidence interval for the average time served (assume jail time follows a normal distribution with standard deviation 3 years).

At 95% confidence interval, the z score is 1.96. Using the formula:

Confidence Interval = x ± z s / sqrt (n)

where x is the average time served, s is standard deviation and n is number of samples

Confidence interval = 7.5 ± (1.96 * 3) / sqrt (400)

Confidence interval = 7.5 ± 0.294

Confidence interval = 7.206 to 7.794

step-by-step explanation:

always plug in x. in this case, x equals 4.

i'm going to first solve 4(2+3x)

1) 4(2+3(4)) use pemdas to solve.

i'm going to multiply whats in the parenthesis first, so 3 times 4=12.

2)4 (2+12) i'm then going to multiply 4 by both numbers in the parenthesis (because multiplying comes before adding)

4 times 2= 8.   4 times 12= 48

4) (8+48)= 56 (answer)

i'm then going to solve 8+12x and plug in 4 for x.

1) 8 +12(4)

multiplying comes before adding, so i'm gonna multiply 12 and 4.

12 times 4= 48.

2) 8+48=56

both equal the same!

step-by-step explanation:

3024 rhe base is what up in worry about