Question 1102506: please help me solve this
1. For a certain urban area, it was found that in a sample of 6 months, an average of 31 burglaries occurred each month. The standard deviation was 4. find the 90% confidence interval of the true mean number of burglaries each month.
2. A sample of 20 tuna showed that they swim an average of 8.6 miles per hour. The standard deviation for the sample was 1.6. find the 95% confidence interval of the true mean.
Answer by Boreal(15235)   (Show Source):
You can put this solution on YOUR website! CI is mean +/- t (df, value)*s/sqrt(n)
for the first, it is 31 +/- t(df=31,0.95)*4/sqrt(31)
This is 31 +/- (1.70*4/sqrt(31))
That is 31+/-1.22
(29.78, 32.22) burglaries
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second is done same way
CI is 8.6 +/-2.093*1.6/sqrt(20)
=8.6+/-0.75
(7.85, 9.35) speed in mph
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