Cancel 0.8
10
1.2
1.4
1.6
1.8
2.0
0.2881
0.3413
0.3849
0.4192
0.4452
0.4641
0.4772
2.8 0.4974
3.0 0.4987
3.2 0.4993
3.4 0.4997
36 0.4998
3.8 0.4999
4.0 0.5000
A day care program has an average daily expense of $75.00. The standard deviation is $5.00. The owner takes a
sample of 64 bills. What is the probability the mean of his sample will be between $70.00 and $80.00?
Step 1. Calculate a z-score for $70.00
Step 2. Give the probability for step 1.
%
Step 3. Calculate the z-score for $80.00
Step 4. Give the probability for step 3.
%
Step 5. Add the probabilities from steps 2&4.
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