Question

The thicknesses of 13 randomly selected linoleum tiles were found to have a standard deviation of 4.76. Construct the 90% confidence interval for the population standard deviation of the thicknesses of all linoleum tiles in this factory. Round your answers to two decimal places.

Answer 1

Solution :

Given that,

s = 4.76

s² = 22.6576

²_L = ²_/2,df = 21.026

²_R = ²_{1 - /2,df} = 5.226

The 90% confidence interval for is,

(n - 1)s² / ²_/2 < < (n - 1)s² / ²_{1 - /2}

  12 * 22.6576 / 21.026 < < 12 * 22.6576 / 5.226

3.60 < < 7.21

(3.60 , 7.21)