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The Problem |
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The average number of gallons of lemonade consumed by the football team during a game is 20, with a standard deviation of 3 gallons. Assume that the variable is normally distributed. When a game is played, find the probability of using a) Between 20 and
25 gallons |
b). Less than 19 gallons
From the text of
the problem we know that 
=
20 and that 
=
3. The TI84 calculator provides a program to compute the probabilities
of normal distributions. We use the function:
Since we need the
area under the normal curve where x < 19 gallons, we let 
=
-E99 and 
=
19 . (Note: Remember to get the E in -E99, we press 2nd 
.)
From the calculator home screen, press 2nd VARS[DISTR], press 2 to select 2:normalcdf(.Type - 2nd , 99 ENTER, 19 ENTER, 20 ENTER, 3 ENTER and then press ENTER twice more. See the results below.
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Thus the P(x < 19) = 0.3694
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