Question
A sum doubles itself in 16 years, then in how many years will it triple itself; rate of interest being simple
Answer: Option A Answer: (a)Case IPrincipal = Rs. xInterest = Rs. xRate = ${SI × 100}/\text"Principal × Time"$= ${x × 100}/{x × 16} = 25/4%$ per annumCase IIInterest = Rs. 2xTime = ${SI × 100}/\text"Principal × Rate"$= ${2x × 100 × 4}/{x × 25}$ = 32 yearsUsing Rule 3,R = ${(n - 1)}/T × 100%$= ${(2 - 1)}/16 × 100%$= $25/4 % = 6{1}/4%$Now, T = ${(n - 1)}/R × 100%$= ${(3 - 1)}/{25/4} × 100$= $800/25$ = 32 years.
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