Your answer: 122
First we have to put the data in ascending order.
49, 56, 68, 72, 83, 89, 97, 115, 122, 139, 142.
I added spaces around the 89 because that’s the median/middle number, and it splits the data into upper and lower halves. The first quartile is the middle number of the bottom half (68), and the third quartile is the middle number of the top half (122)
Does that all make sense? Happy to answer questions.
If they ask for inner quartile range/IQR, that is the 3rd quartile minus the 1st quartile. 122 - 68 = 54