Measures of Central Tendency
- A company has four locations at which customers were surveyed about their satisfaction levels. The following table shows the average customer rating for each of the four locations along with the number of customers at each location who responded. Calculate the average customer rating for the entire company.
- The following table shows the number of wins each season for the Green Bay Packers from 2003–2009. Determine the variance and standard deviation for these data.
- Question to think: what’s probability of -2.54 £ Z £54, or Prob (-2.54 £ Z £ 2.54)?
- The average U.S. monthly cable bill in 2009 was $75, according to Centris, a marketing research firm. Assume monthly cable bills follow a normal distribution with a standard deviation of $9.50.
- a) What is the probability that a randomly selected bill will be
1) less than $70?
2) less than $80?
3) exactly $75?
4) between $65 and $85?
- According to the Kaiser Family Foundation, children ranging from ages 8 to 18 averaged 7.5 hours per day using electronic media in 2009 (up from 6 hours in 1999). Assume the population standard deviation is 2.4 hours per day. A random sample of 30 children from this age group was selected, with a sample average of 8.8 hours of electronic media use per day.
- Is there support for this claim using the criteria that were previously discussed?
- According to ESPN, the average weight of a National Football League (NFL) player in 2009 is 252.8 pounds. Assume the population standard deviation is 25 pounds. A random sample of 38 NFL players was selected.
- a) Calculate the standard error of the mean.
- b) What is the probability that the sample mean will be less than 246 pounds?
- Banking fees have received much attention during the recent economic recession as banks look for ways to recover from the crisis. A sample of 30 customers paid an average fee of $12.55 per month on their interest-bearing checking accounts. Assume the population standard deviation is $1.75.
- a) Construct a 95% confidence interval to estimate the average fee for the population.
- b) What is the margin of error for this interval?