Rivet holes are punched in steel beams. To ensure that the rivets will fit and that the joint will have adequate strength, it is necessary to control the standard deviation o the diameter, and measurements are made periodically. Ten measurements are made of nominally 1-inch-diameter holes, and the standard deviation is found to be 0.002 inches. What is the 95% confidence interval on the standard deviation? Required – confidence interval in the standard deviation → Chi-squared distribution. S = 0,002 in., n = 10,  = n – 1 = 9. 95% confidence level:  = 1-0.95 = 0.05.

The 95% confidence interval for the standard deviation of the diameter is (0.0014; 0.0036).

Step-by-step explanation:

We have to calculate a confidence interval for the standard deviation.

The confidence level is 95%.

The size of the sample is n=10.

The sample standard deviation is s=0.002.

The lower limit is calculated as:

The 95% confidence interval for the standard deviation of the diameter is (0.0014; 0.0036).

neither i nor ii 56 / 4.9 = 11.91489362 and 82 / (11+5) =5.125 so i is wrong

ii. (24/8+2) times 3 = 15 and (42+9)/2 =25.5

step-by-step explanation:

56

use this formula:

p(a\b) = p(a and b)/p(b).

take it from here.