Simple interest on a certain sum at a certain annual rate

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Simple interest on a certain sum at a certain annual rate of interest is 16/25 of the sum. If the number representing rate per cent and time in years be equal, then the rate of interest is

Let the rate of interest be r% and principal be P.
According to the question.

16P	=	P × r × r
25	=	100

[∵ r = t numerically]

⇒ r² =	1600
	25

⇒ r = 40÷ 5 = 8%
Second method to solve this question :

Here, n =	16	, R = T
	25

R × R =	16	× 100
	25

R² =	1600
	25

⇒ R² = √	1600
	25

R =	40
	5

R = 8%