In How Much Time, Amount Equal to the Principal? If
Answer: (2) 20 years
Let the principal be P and the rate of interest be R
Simple Interest = P x R x T/100
Where, P = principal , R = rate, & T = time.
According to the question,
30 P /100 = P x R x 6/100
30 P = P x R x 6
30 = R x 6
R = 30 /6
R = 5 %
Then, P = P x 5 x T/100
T = 100/5
T = 20 years
Hence, the answer is (2) 20 years.