statistik

can you show me the calculation ;)

The life expectancy of computer terminals is normally distributed with a mean of 4 years and standard deviation for 10 months.

a. What is the probability that a randomly selected terminal will last more than 5 years?

b. What percentage of terminals will last between 2.5 years and 4.5 years?

c. 80 percent of terminals will last at least how many years?

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  1. Convert all values either into months or years.

    Z = (score-mean)/SD

    Find table in the back of your statistics text labeled something like "areas under normal distribution" to find the proportions related to the Z scores. To get percentages, multiply by 100.

    c. Reverse process to find Z score and calculate.

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  2. 0.102

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