Interquartile Rang concept / Problem?

Question

If a set of data consists of only the first ten positive mulitple of $5$, what is the interquartile range of the set ?

I have tried to solve but my answer is wrong..

Answer 1

For your data $\{5, 10, 15, 20, 25, 30, 35, 40, 45, 50\}$ we have $Q_1 =15$, $Q_2 = \frac{55}{2}$, and $Q_3 = 40$. Thus the $IQR=Q_3 - Q_1 = 40-15=25$