Statistics Chapter Review

If a distribution is skewed to the right with no outliers, 

• mean<median
• mean>median
• mean=median
• can not determine

Which of the following statements about this distribution is not correct?

• The histogram is skew right.
• The median is less than the $20.
• The IQR is $35.
• The mean is greater then the median. 

The scores on a statistics exam had a mean of 81 and a standard deviation of 9. One student was absent on the test day, and his score wasn't included in the calculation. If his score of 84 is added to the distribution of scores, what would happen to the mean and standard deviation?

• mean will increase, standard deviation will increase
• mean will increase, standard deviation will decrease
• mean will increase, standard deviation will stay the same
• mean will decrease, standard will decrease 

True or false: The IQR is a resistant measure of spread.

• True 
• False

The mean salary of all female workers is $35,000. The mean salary of all male workers is $41,000. What must be true about the mean salary of all workers?

• It must be $38,000.
• It must be larger than the median salary.
• It could be any number between $35,000 and $41,000.
• It must be larger than $38,000.

Which of the following is NOT true?

• There are two outliers in the data.
• The median IQ score is 100.
• The IQR is 40.
• 25% of IQ scores are below 93.

Which of the following is NOT true.

• There is more variability in Macaw lifetimes in the wild. 
• 25% of Macaws in Captivity live longer than 80 years.
• 75% of Macaws in captivity live longer than 73 years.
• The mean lifetime for Macaws in the Wild is 54.

15 people took a CPR test. What was the median score?

• 5-10
• 10-15
• 15-20
• 20-25

When a distribution is skewed, which measures of center and spread are most reliable?

• Mean and standard deviation
• Mean and IQR
• Median and standard deviation
• Median and IQR

If a distribution is symmetrical, which of the following is true?

• The mean must be less than the median.

• The mean must be greater than the median.

• It’s impossible to tell which of the above statements is true without seeing the data.

• The mean and median must be equal.