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
a) Between 20 and 25 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 between 20 and 25, or 20 < x < 25, we let = 20 and = 25.
From the calculator home screen, press 2nd VARS[DISTR], press 2 to select 2:normalcdf(. Type 20 ENTER, 25 ENTER, 20 ENTER, 3 ENTER and then press ENTER twice more. See the results below.
Thus the P(20 < X < 25) = 0.4522
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