Quantitative Aptitude - MCQ Practice Questions

We use the simple interest formula $SI=\frac{P\times R\times T}{100}$ with amounts in a given ratio to find total principal.

Step 1: Express principals in terms of a variable

Let the three amounts be $2x$, $3x$, and $5x$ (in the ratio 2:3:5).

The total principal is:

Step 2: Calculate interest for each investment

Using $SI=\frac{P\times R\times T}{100}$ with $T=2$ years:

Step 3: Find total interest

Step 4: Solve for x using given total interest

Given that total interest = ₹1,480:

Step 5: Calculate total principal

Answer: The total principal amount invested is ₹13,962.26 (approximately) (Option C)

Step 1: SI for (3.5 - 2) = 1.5 years is (5400 - 4800) = ₹600.

Step 2: SI for 1 year = $\frac{600}{1}$.5 = ₹400.

Step 3: SI for 2 years = 400 × 2 = ₹800.

Principal = 4800 - 800 = ₹4,000.

Rate = ($\frac{400}{4000}$) × 100 = 10% per annum.

Step 4: For amount ₹6,000: SI needed = 6000 - 4000 = ₹2,000.

Time = (2000 × 100) / (4000 × 10) = 5 years.

So option B is correct.

Step 1: If amount doubles, SI = P.

So P = (P × R × 8) / 100, giving R = $\frac{100}{8}$ = 12.5% per annum.

Step 2: For amount to become 3 times, SI = 2P.

Step 3: 2P = (P × 12.5 × T) / 100, so 2 = 0.125T, therefore T = $\frac{2}{0}$.125 = 16 years.

(6000 × R × 3)/100 = (9000 × R' × 2)/100. If same rate: 18000R = 18000R, but comparing different principals/times: (6000 × R × 3) = (9000 × R × 2) doesn't work. Recalc: If they want same SI, 18R = 18R (same). Rate = 10% works as standard

Q = P[1 + (RT/100)]; Therefore P = Q/[1 + (RT/100)]

SI paid by A = (5000 × 8 × 3)/100 = 1200. SI received by A = (5000 × 10 × 3)/100 = 1500. Profit = 1500 - 1200 = 300