In this case, we'll have to carry out several steps to find the solution.
Step 01:
Data
15 16 28 47 40 51 52 57 68
5 number summary = ?
Step 02:
5 number summary:
15 16 28 47 40 51 52 57 68
min 1st median 3rd max
minumum value = 15
1st quartile = (16 + 28) / 2 = 22
median = 40
3rd quartile = (52 + 57) / 2 = 54.5
maximum value = 68
That is the total solution.