Question

Specifications for a piece of material used in the manufacture of a bed mattress require that the piece be between a Lower and Upper value (in inches) centered around the process mean. The process that produces the piece yields a mean of 25 and a standard deviation of 0.6 inches. The distribution of output is normal. Within what values will 94.87 percent of sample means fall, if samples of n = 10 are taken and the process is in control?

Question 2 options:

	23.03 , 26.969
	24.23 , 25.769
	23.83 , 26.169
	24.63 , 25.369
	None of the Above

Answer 1

Solution :

Given that,

Sample size = n = 10

Z/2 = Z0.0256 = 1.95

Margin of error = E = Z/2* ( /n)

= 1.95 * ( 0.6 / 10)

Margin of error = E = 0.370

At 94.87% confidence interval estimate of the population mean is,

- E < < + E

25 - 0.370 < < 25 + 0.370

24.63 < < 25.369

( 24.63 , 25.369 ), Option 4 th is correct .