Sat scores have a mean of 500 and a standard deviation of 100. let's contine with the above example: if we wanted a 95% confidence interval to be from 490 to 510, how big would the sample have to be

385

Step-by-step explanation:

Given that :

Mean, m = 500

Standard deviation, s = 100

Zcritical at 95% = 1.96

Confidence interval, C2 - C1 ; 510 - 490

Using the relation :

n = (2 * Zcritical * s) / (C2 - C1)

n = sample size

n = [(2 * 1.96 * 100) / (510 - 490)]^2

n = (392 / 20)^2

n = 19.6²

n = 384.16

n = 385

$25

step-by-step explanation:

25 - 4.50 = 20.5

20.5 / 2 = 10.25

10.25 + 10 = 20.25

20.25 - 12.50 = 7.75

therefore the answer is $25 as shown as the first number.

18.75 gallons

step-by-step explanation: