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Examoogle • User • info@examoogle.com • EE-2024-8821
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In what duration will a sum of money triple itself at 25% per annum simple interest?
6 years
8 years
10 years
12 years
8 years
Given: Principal P triples, rate = 25% per annum simple interest, find time T
Principal P triples, rate = 25% per annum simple interest, find time T
P(1+100RT)=3P
Since amount triples, interest must be twice the principal; use RT=200, so T=200/25=8 years.
Mixing up total amount with interest and mistakenly applying compound interest formula.
Interpret the condition
The amount must become three times the principal, so the interest earned should be twice the principal.
3P=P+SI
Write SI formula
Simple interest is given by SI = P·R·T/100.
SI=100PRT
Set SI equal to twice the principal
Because interest must equal 2P, we have 100PRT=2P.
100PRT=2P
Solve for time T
Cancel P and multiply by 100: R T = 200 ⇒ T = 200/R = 200/25 = 8 years.
T=25200=8
B is correct because the calculated time is 8 years, matching option B.
The same rate‑time‑principal relationship is used in mixture and work problems, so mastering this shortcut helps in those topics too.