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SOLVE BOTH PARTS WITHOUT USING MATLAB PLEASE AAA Controls makes a switch that is

ID: 3157996 • Letter: S

Question

SOLVE BOTH PARTS WITHOUT USING MATLAB PLEASE

AAA Controls makes a switch that is advertised to activate a warning light if the power supplied to a machine reaches 100 volts. The voltages at which a warning occurs are normally distributed. A random sample of 75 switches is tested, and the mean voltage at which a warning occurs is 98 volts, and the standard deviation was 6 volts.

a. Create a 90% confidence interval on the true mean voltage at which a warning occurs.

b. Create a 95% confidence interval for the variance ^ 2 .

Explanation / Answer

a)

alpha / 2 = 0.05   Z= 1.64

I: 98 +/- 1.64 * 6 / srqt 75

98 +/- 1.136

96.864 < miu < 99.136

b)

alpha / 2 = 0.025   df=74

X^2 74,0.025 = 95.032

X^2 74,0.975 = 48.758

74 * 6^2 / 95.032 < sigma2 < 74 * 6^2 / 48.758

28.03 < sigma^2 < 54.637