Making Sense of Data: A Practical Guide to Exploratory Data Analysis and Data Mining

5.6 EXERCISES

Table 5.15 presents the ages for a number of individuals.

1. Calculate the following statistics for the variable Age:
   1. Mode
   2. Median
   3. Mean

      Table 5.15. Table with variables Name and Age

      Name	Age
      P.Lee	35
      R.Jones	52
      J.Smith	45
      A.Patel	70
      M.Owen	24
      S.Green	43
      N.Cook	68
      W.Hands	77
      P.Rice	45
      F.Marsh	28

   4. Range
   5. Variance
   6. Standard deviation
   7. z-score
   8. Skewness
   9. Kurtosis
2. An insurance company wanted to understand the time to process an insurance claim. They timed a random sample of 47 claims and determined that it took on average 25 minutes per claim and the standard deviation was calculated to be 3. With a confidence level of 95%, what is the confidence interval?
3. An electronics company wishes to understand, for all customers that purchased a computer, how many will buy a printer at the same time. To test this, the company interviews a random sample of 300 customers and it was determined that 138 bought a printer. With a confidence level of 99%, what is the confidence interval for the proportion of customers buying a printer at the same time as a computer?
4. A phone company wishes to make a claim that the average connection time in the US is less than two seconds (i.e. the time after you dial a number before the call starts to ring). To test this, the company measures 50 randomly selected calls and the average time was 1.9 seconds with a standard deviation of 0.26. Using this information and a 95% confidence level:
   1. Specify the null and alternative hypothesis ...