The standard deviation of test scores on a certain achievement test is 10.5 . A random sample of 90 scores on this test had a mean of 72.1 . Based on this sample, find a 90% confidence interval for the true mean of all scores. What is the lower limit of the 90% confidence interval?

hope it

step-by-step explanation:

x^(1/6) · x^(1/6) · x^(1/6)   ·x^(1/6) = x^(4/6)   since we add the exponents

4/6 can be simplified to 2/3

the simplified form is x^(2/3)

a variable is any characteristics, number, or quantity that can be measured or counted. a variable may also be called a data item. hope i !