You work for a consumer advocate agency and want to find the mean repair cost of a washing machine. As part of your study, you randomly select 30 repair costs and find the mean to be $100.00. The standard deviation of the sample is $25.20. Calculate a 90% confidence interval for the population mean.

90% confidence interval for the population mean is between a lower limit of $92.18 and an upper limit of $107.82.

Step-by-step explanation:

Confidence interval for a population mean is given as mean +/- margin of error (E)

mean = $100

sd = $25.20

n = 30

degree of freedom = n-1 = 30-1 = 29

confidence level (C) = 90% = 0.9

significance level = 1 - C = 1 - 0.9 = 0.1 = 10%

critical value (t) corresponding to 29 degrees of freedom and 10% significance level is 1.699

E = t×sd/√n = 1.699×25.20/√30 = $7.82

Lower limit of population mean = mean - E = 100 - 7.82 = $92.18

Upper limit of population mean = mean + E = 100 + 7.82 = $107.82

90% confidence interval is ($92.18, $107.82)

c. 65°

step-by-step explanation:

we are given a triangle with two known angles, 62° and 53°, while the third angle x is unknown and we are to find its value.

we know that the sum of angles in a triangle is equal to a total of 180 degrees. so we can write it as:

x + 62° + 53° = 180°

solving to find the value of x:

x = 180 - (62 + 53) = 65°

therefore, the value of x in this triangle is 65°.