Past experience has indicated that the breaking strength of yarn used in manufacturing drapery material is normally distributed. A random sample of 8 specimens is tested, and the breaking strength for each specimen is recorded. Assuming known population standard deviation, the width of a 95 percent confidence interval was found to be 2.694. What was the value of population standard deviation used in calculating the confidence interval?

the value of population standard deviation is 3.87

Step-by-step explanation:

From the information given,

Number of sample, n = 8

For a confidence level of 95%, the corresponding z value is 1.96. This is determined from the normal distribution table.

We will apply the formula

Confidence interval

= mean ± z ×standard deviation/√n

Since confidence interval = 2.694,

It becomes

2.694 = 1.96 × standard deviation/√8

Dividing both sides of the equation by 1.96, it becomes

1.37 = standard deviation/√8

Standard deviation = 1.37 × √8

Standard deviation = 3.87

trapezoid

step-by-step explanation:

first i plotted all my points on a grid graph

i made sure all of them were in the correct quadrant

then i saw it was a trapezoid or a quadrilateral