please help me to solve these problems, please.

hello, could you please help me to answer the following two questios?

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.