Question

Q#9: The download time of a resource web page is normally distributed with a mean of 6.5 seconds
and a mean deviation of 2.3 seconds.
(a): What proportion of page downloads take more than 7 seconds? (05)
(b): How many seconds will it take for less than 68% of the downloads to be completed?

Answer 1

Here µ=6.5 and     σ=2.3

a)

We will use Ti83/84

Press   2ND...VARS...normalcdf

Enter values as

Result is :

Proportion of page downloads take more than 7 seconds is 0.4139517374

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b)

In Ti83/84

Press 2nd...VARS...invNorm

Enter values as

result is:

7.575707243 seconds will it take for less than 68% of the downloads to be completed.

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Note: Please check the rounding instructions before intering values.