Engineering Fundamentals: An Introduction to Engineering, 4th ed.c

Example 19.7 For Example 19.4, determine the probability that it will take a person longer than 10 minutes

to assemble the computer parts.

For this problem, the zscore is

From Table 19.11, A 0.1331. Since we wish to determine the probability that it takes

longer than 10 minutes to assemble the part, we need to calculate the area, 0.5 0.1331 

0.3669, as shown in Figure 19.9. The probability that it will take a person longer than 10 min-

utes to assemble the computer part is approximately 0.37.

z

xx

s



10 9.22

2.28

0.34

19.5 Normal Distribution 649

z  0.97 z  0.78

A  0.3340  0.2823  0.6163

■Figure 19.8

Area under the probability distribution curve for Example 19.6.

The value 7 is below the mean value (9.22) and thezvalue corresponding to 7 is deter-

mined from

From Table 19.11,A0.3340. Similarly, the value 11 is above the mean value and the

zscore corresponding to 11 is computed from

From Table 19.11, A0.2823. Therefore, the probability that it will take a person

between 7 and 11 minutes to assemble the computer part is 0.3340 0.2823 0.6163 as

shown in Figure 19.8.

z

xx

s



11 9.22

2.28

0.78

z

xx

s



7 9.22

2.28

0.97

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