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

.mp4 files, because, video

a) one student is chosen from classroom a, then a student is chosen from classroom b.  

step-by-step explanation:

independent events are ones in which the probability of one event does not affect the probability of the second event.

one student is chosen from classroom a; this does not affect the chances of choosing a student from classroom b.   this makes these independent events.

when one card is chosen from a standard deck and then set aside before a second card is chosen, the probability of the second card being chosen changes.   this makes them dependent events.

when one student is chosen from classroom a and then a second student is chosen from classroom a, the probability of choosing the second student changes.   this makes them dependent events.

when a letter is chosen from the alphabet and then a second letter is chosen, the probability of choosing the second letter changes.   this makes them dependent events.