Quantitative Aptitude - MCQ Practice Questions

x% of 400 = 20% of 500. (x/100) × 400 = 0.2 × 500. 4x = 100. x = 25.

B takes 30 days, so B's rate = $\frac{1}{30}$. A works twice as fast, so A's rate = $\frac{2}{30}$ = $\frac{1}{15}$. Combined rate = $\frac{1}{30}$ + $\frac{1}{15}$ = $\frac{1}{30}$ + $\frac{2}{30}$ = $\frac{3}{30}$ = $\frac{1}{10}$. Time taken = 10 days.

35% of x = 105. x = $\frac{105}{0}$.35 = 300. 65% of 300 = 0.65 × 300 = 195.

Speed = $\frac{200}{5}$ = 40 km/h. Distance in 8 hours = 40 × 8 = 320 km.

Boat speed = (Downstream + Upstream) / 2 = (20 + 12) / 2 = $\frac{32}{2}$ = 16 km/h.

Profit % = [(140 × 85)/100 - 100] = [119 - 100] = 19%

Number = $\frac{180}{0}$.45 = 400. So 80% of 400 = 320

SI = (8000 × 12 × 1.5)/100 = 1440. Amount = 8000 + 1440 = Rs. 9440

Combined rate = $\frac{1}{24}$ + $\frac{1}{36}$ = (3+2)/72 = $\frac{5}{72}$. Time = $\frac{72}{5}$ = 14.4 minutes

Speed in m/s = 72 × $\frac{5}{18}$ = 20 m/s. Distance = 20 × 25 = 500 m

When a boat moves in a river, its effective speed changes based on the stream direction. We use the formulas: Downstream speed = boat speed + stream speed, and Upstream speed = boat speed − stream speed.

Step 1: Calculate Downstream Speed

Downstream means the boat moves with the stream (both speeds add):

Step 2: Calculate Upstream Speed

Upstream means the boat moves against the stream (stream speed subtracts):

Step 3: Find the Ratio

The ratio of downstream to upstream speed is:

This simplifies to $3:2$.

**Answer: The ratio of downstream to upstream speed is $3:2$ (Option B)**

Let CP = 100. MP = 160. After 25% discount, SP = 160 × 0.75 = 120. Profit% = (120-100)/100 × 100 = 20%

Let initial salary = 100. After 15% increase = 115. After 10% decrease = 115 × 0.90 = 103.5. Net change = 3.5% increase

SI = 50000×12×$\frac{2}{100}$ = ₹12,000. CI = 50000(1.12)² - 50000 = ₹12,720. Difference = ₹720.

Rate = $\frac{1}{20}$ + $\frac{1}{30}$ - $\frac{1}{60}$ = $\frac{3}{60}$ + $\frac{2}{60}$ - $\frac{1}{60}$ = $\frac{4}{60}$ = $\frac{1}{15}$. Time = 15 minutes.

Distance = 150 + 250 = 400m. Speed = $\frac{400}{20}$ = 20 m/s = 20×3.6 = 72 km/h.

Upstream speed = $\frac{24}{6}$ = 4 km/h. Downstream speed = $\frac{24}{3}$ = 8 km/h. Current = (8-4)/2 = 2 km/h.

MP = 80×1.25 = ₹100. SP = 100×0.9 = ₹90. Profit = $\frac{10}{80}$ × 100 = 12.5%.

Increase = 48000 - 40000 = 8000. Percentage = $\frac{8000}{40000}$ × 100 = 20%.

Distance = 5×6 = 30 km. New time = $\frac{30}{6}$ = 5 hours. Time saved = 6-5 = 1 hour.