(willing to give 30 points! picture included)
i am super stuck on this one and i really need with this problem a the moment, i would appreciate it so much.

joel surveyed 13 classmates to find out the number of days it had been since the last time they were at a grocery store.

a. what was the median number of days represented on joel's plot?

b. what is the interquartile range of number of days represented on joel's plot.

c. by how much does the mean of joel's second data set change in comparison with the mean of the data set in his original survey? explain how to determine the change in means without calculating the mean of either data set.