1 The distribution of purchase amounts of customers of a popular retail store is normal with a mean of $25 and a standard deviation of $8.

a. What percentage of customers spends less than $35?
b. What percentage of customers spends between $15 and $35?
c. Find the dollar amount such that 80% of customers spend at least this amount.

3. The lifetime of Kenless washing machines is normally distributed with a mean of 4 years. Only 15% of these machines last at least 5 years. What is the standard deviation of the lifetime of a Kenless washing machine?

4. Many drivers on US interstate highways do not observe the speed limit. Assume that the actual rates of speed driven in the US are normally distributed with a standard deviation of 5 miles per hour (mph).

If 20% of all US drivers travel at 65 mph or more, what is the average?

Solution Summary

Calculations based on Normal distribution such as probability in an interval.

... The solution gives the details of calculation of probability of a random variable in ... Given a normal distribution with µ = 100 and σ = 10, what is the ...

... on conducting a case study of normal distributed data ... All formula and calculations are shown and explained ... Description: The dataset provided here is based on a ...

... score of 70% on the exam based solely upon ... get the answer shown in the formula bar. ... preceding information and modeling this situation as a normal distribution. ...

... If you would like the normal distribution table so you can ... squares method to find the regression equation to predict the advertising costs based on the ...

... the following sigma levels correspond to, based on a ... this function returns the standard normal cumulative distribution... What is the point of these calculations? ...

...Based on this table find probability that randomly ... 11. Calculate expressions with factorials: 6!/4 ... 12. Normal Distribution has mean 200 and standard deviation 40 ...

... Using a t-test, and assuming a fairly normal distribution, do the ... 3.Calculate the t-statistic (show your work). 4.Based on a 95% confidence level, is the null ...

... used in research, a bivariate normal distribution is very ... and the alternative hypothesis based on your ... taker as 0.05 /0.01 =0.05 3. Calculate the value ...

... events, while a z- statistic has a standard normal distribution, based on a distribution of sample ... score and the overall mean by this formula: z = , where z ...