1. A study of long-distance phone calls made from General Electric\'s corporate
ID: 3328847 • Letter: 1
Question
1. A study of long-distance phone calls made from General Electric's corporate headquarters in Fairfield, Connecticut, revealed the length of the calls, in minutes, follows the normal probability distribution. The mean length of time per call was 3.7 minutes and the standard deviation was 0.60 minutes.
1. A study of long-distance phone calls made from General Electric's corporate headquarters in Fairfield, Connecticut, revealed the length of the calls, in minutes, follows the normal probability distribution. The mean length of time per call was 3.7 minutes and the standard deviation was 0.60 minutes.
a) As part of her report to the president, the director of communications would like to report the length of the longest (in duration) 5% of the calls. What is this time? (Round z-score computation to 2 decimal places and your final answer to 2 decimal places.) ___________2. The employees of Cartwright Manufacturing are awarded efficiency ratings. The distribution of the ratings approximates a normal distribution. The mean is 418, the standard deviation 64. What is the area under the normal curve between 418 and 486?
a) 0.5000
b) 0.3560
c) 0.8560
d) 0.0356
Explanation / Answer
Mean is 3.7 and s is 0.6
Longest 5% means value at 95% from the bottom, we need to find the z value from normal distribution table as value for 0.95 which is 1.65
thus the value is mean+s*z =3.7+1.65*0.6=4.69
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