The difference between compound interest and simple interest at the same rate on Rs 5000 for 2 years is Rs 72. The rate of interest per annum is:___________?

A. 720
B. 1440
C. 1860
D. 2160
In the word, “MATERIAL” there are three vowels A, I, E.
If all the vowels are together, the arrangement is MTRL’AAEI’.
Consider AAEI as one unit. The arrangement is as follows.
M T R L A A E I
The above 5 items can be arranged in 5! ways and AAEI can be arranged among themselves in 4!/2! ways.
Number of required ways of arranging the above letters = 5! * 4!/2!
= (120 * 24)/2 = 1440 ways.