15 Mastering a computer program The number of training units

.15 Mastering a computer program. The number of training units that must be passed before a complex computer soft- ware program is mastered varies from one to five, depend- ing on the student. After much experience, the software manufacturer has determined the probability distribution

Solution

a)

Consider the table:

Thus, mean = 2.9 [answer]

Now, the median is where the cumulative probability is at least 0.50.

Thus, median = 3 [answer]

Thus, the arithmetic mean number of training units is 2.9, wchile the middle entry when we summarize the data from lowest to highest is 3.

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b)

Using the cdf table:

If at least 75%, the number of training units is at least 4. [answer, 4]

If at least 90%, the number of training units is at least 5. [answer, 5]

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c)

Consider the table:

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As we can see, the new answers for parts a and b are:

Mean = 2.15

Median = 2

At least 75% = 3 units

At least 90% = 3 units

x	P(x)	x P(x)
1	0.1	0.1
2	0.25	0.5
3	0.4	1.2
4	0.15	0.6
5	0.1	0.5