GIVEN:
A sum of money doubles itself in 7 years.
CONCEPT:
Simple interest concept.
FORMULA USED:
SI = (PRT/100)
See Also
Understanding the 10-Year Rule — AscensusHow to get 11.5% on your moneyWhere the “7% Return” Comes from in Investing — Millennial Money with KatieFinancial Experts Share 12 Secret Moves to Double Your 401(k)Where,
P = Principal, R = Rate, T = Time
CALCULATION:
Suppose Principal = Rs. P, Amount = 2P, Time = 7 and Rate = R% (Suppose)
⇒ SI = 2P – P = Rs. P
Now,
P = (P × R × 7/100)
⇒ R = 100/7%
Now, we want the money to be quadruple i.e. 4 times.
⇒ Amount = 4P and SI = 3P
Suppose time = T
So,
3P = (P × 100/7 × T)/100
⇒ T = 21
∴ The money will quadruple itself in 21 years.
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