Certain sum becomes 3 times it self at compound interest in 10 years. In how many years it becomes 9 times?  Choose the correct choice from the following answers.
A) 24	B) 20	C) 22	D) 28	E) 25
P(1 + R/100)(power10) = 3P   =&gt; P(1 + R/100)(power10) = 3   Let P(1 + R/100)(power n) = 9P   =&gt; (1 + R/100)(power n) = 9   =&gt; 3(power 2) = [(1 + R/100)(power10)](power2)   =&gt; (1 + R/100)(power n) =&gt; (1 + R/100)(power 20)   =&gt; n = 20 Years.   Answer is 20.
<result>B</result>
Certain sum becomes 3 times it self at compound interest in 10 years. In how many years it becomes 9 times?