A sum doubles in seven years at simple interest. In how many years will the sum become five times the original sum?
Answer & explanation
Correct answer: option 3
Given :-
Sum doubles in seven years at simple interest.
Let sum = P , Amount = 2P
So , SI= 2P - P = P
P = \(\frac{P ×Rate × 7}{100}\)
Rate = \(\frac{100}{7}\)%
Now ,
Sum become 5 times of itself . SO , SI = 5P - P = 4P
4P = \(\frac{P × 100 × Time }{100 × 7}\)
Time = 28 years