Question

Normal
mu	2.09
sigma	0.21
xi	P(X<=xi)
1.61	0.0111
1.76	0.0580
2.39	0.9234
2.53	0.9819
P(X<=xi)	xi
0.10	1.8209
0.20	1.9133
0.30	1.9799
0.40	2.0368

Normal
mu	2.09
sigma	0.24
xi	P(X<=xi)
1.61	0.0228
1.76	0.0846
2.39	0.8944
2.53	0.9666
P(X<=xi)	xi
0.10	1.7824
0.20	1.8880
0.30	1.9641
0.40	2.0292

The mean weight for a part made using a new production process is 2.09 pounds. Assume that a normal distribution applies and that the standard deviation is 0.21 pounds. Based on this paragraph of text, use the correct excel output above to answer the following question.

The probability is .80 that weight for a part (in pounds) made using the new production process will be between two values equidistant from the mean. Find the upper value (in pounds).

	a.	2.1508
	b.	2.3591
	c.	2.1432
	d.	None of the answers is correct
	e.	2.3976

Answer 1

0.80 area is in the middle so 0.10 area will be in each tail. Corresponding right tailed z value = 1.28

Hence,

Upper value = 2.09 + 1.28*0.21 = 2.3591

Option B is correct.