The ages of 20 dancers who responded to a call to audition for a musical comedy are listed in the box below. Use the raw data set to answer the listed questions.

16 16 16 17 17 18 18 18 19 19 20 21 22 23 23 24 25 25 26 27

1-What is the 40th percentile?

2-What percent of the data of the ages of the dancers set is within one standard deviations of the mean?

3- If you were to group the data into classes using the interval 16 to 21 as the first class how many data would be in the third class?

Thank you.

2. Originally Posted by jhonwashington

16 16 16 17 17 18 18 18 19 19 20 21 22 23 23 24 25 25 26 27

1-What is the 40th percentile?

Thank you.
$40\% \times 20 = 8$ so the 40th percentile will lay between the 8th and 9th number

Originally Posted by jhonwashington

16 16 16 17 17 18 18 18 19 19 20 21 22 23 23 24 25 25 26 27

2-What percent of the data of the ages of the dancers set is within one standard deviations of the mean?
The standard deviation for this data set is 3.6 and the mean is 20.5 so you have to count how many numbers lay in the interval (20.5-3.6,20.5+3.6) and find that as a percentage of the total amount of numbers.

3. thank you

Thank you very much pickslides!
just two more things....

you say that the 40th percentile will lay between the 8th and 9th number, so is that the answer? or should I add 18+19 and divide by 2 to get 18.5 ?