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Q- A manufacturing producing a product time is normally distributed. A random sa

ID: 3070638 • Letter: Q

Question

Q- A manufacturing producing a product time is normally distributed. A random sample has a mean of 40 minutes and a standard deviation of five minutes. Estimate the percent of products that are produced between 35 and 40 minutes. The first step in solving this problem is to calculate the Z scores

(in the previous example I provided the Z-Scores for you, this time you will have to calculate them first. This is a simple process once you have the formula). The Z-score formula is as follows: Z = x-/)

(In this example, X= 35, 40 minutes, and = 30, and =5) Remember you need the Z score for 35 minutes and the Z score for 40 minutes

What are the calculated Z-scores for

X= 35? ____________

X= 40? ____________

Using the Appendix II on page 711 of the text or Minitab, or Excel, what is the

area under the curve for the above calculated Z-scores?

Area under the curve for Z-score X=35? ______________

Area under the curve for Z-score X=40? ______________

What is the difference, in other words, what is the approximate percentage of

time that this manufacturer can produce a product between 35 and 40 minutes

based on the data that you were given and your calculations of the z-score using

the normal distribution table? _______________

Based upon your answer do you believe this manufacture as the capability to

consistently produce a product between 35 and 40 minutes?

(Note: the answer has to be typed, not hand written nor in a picture.) Thank you.

Explanation / Answer

Given that

= 40, and =5

p ( 35 < x < 40 ) =?

sol :

p ( 35 < x < 40 )

= p( (35 - 40) / 5 < z < ( 40 - 40) / 5 )

= p ( -1 < z < 0 )

= p ( z <0 ) - p ( z < -1 )

= 0.5 - 0.1587

= 0.3413 or 34.13%