Quantitative Aptitude - MCQ Practice Questions

Sum of 5 friends = 5 × 24 = 120. Sum of 4 friends = 4 × 22 = 88. Age of friend who left = 120 - 88 = 32 years.

Total cost = (10 × 50) + (15 × 40) = 500 + 600 = 1100. Total items = 25. Average = $\frac{1100}{25}$ = ₹44.

Sum of 6 numbers = 6 × 18 = 108. Sum of 3 numbers = 3 × 24 = 72. Total sum = 180. Total numbers = 9. New average = $\frac{180}{9}$ = 20.

Total distance = 120 + 180 = 300 km. Total time = 2 + 3 = 5 hours. Average speed = $\frac{300}{5}$ = 60 km/h.

Sum needed for average 85 in 4 subjects = 4 × 85 = 340. Sum of 3 scores = 75 + 82 + 88 = 245. Fourth subject score = 340 - 245 = 95.

To find C's weight, use the definition of average: the sum of all values divided by the count equals the average.

Step 1: Set up the average formula

The average weight of A, B, and C is 70 kg, so:

Step 2: Express the sum of weights

Multiply both sides by 3 to find the total weight:

Step 3: Substitute known values

We know A = 75 kg and B = 68 kg. Substitute into the equation:

Step 4: Solve for C's weight

**Answer: C's weight is $67\text{kg}$ (Option C)**

Upstream speed = $\frac{50}{5}$ = 10 km/h. Downstream speed = $\frac{80}{4}$ = 20 km/h. Boat speed in still water = (10 + 20)/2 = 15 km/h.

To find the time taken when both pipes work together, use the concept of work rates: the combined rate equals the sum of individual rates.

Step 1: Find individual work rates

Pipe A fills the tank in 12 hours, so its rate is $\frac{1}{12}$ tank per hour.

Pipe B fills the tank in 15 hours, so its rate is $\frac{1}{15}$ tank per hour.

Step 2: Find combined work rate

When both pipes work together:

Find the LCM of 12 and 15, which is 60:

Step 3: Calculate time to fill one tank

If the combined rate is $\frac{3}{20}$ tank per hour, then time to fill 1 tank is:

Step 4: Convert to hours and minutes

**Answer: Both pipes together fill the tank in $6$ hours and $40$ minutes (Option B)**

For consecutive odd numbers, the average equals the middle (4th) number. So 4th number = 39. The 7 numbers are: 33, 35, 37, 39, 41, 43, 45. Largest = 45.

Distance in first 2 hours = 50 × 2 = 100 km (which is 25% of total). Total distance = 400 km. Total time at 60 km/h = $\frac{400}{60}$ = 6.67 hours.

Interest on first = 5,000 × 8 × $\frac{2}{100}$ = 800. Interest on second = 7,500 × 12 × $\frac{2}{100}$ = 1,800. Total interest = 2,600. Average rate = (2,600 × 100) / (12,500 × 2) = 10.4%.

Increase in total age = 38 - 28 = 10. If average increases by 2, then group size = $\frac{10}{2}$ = 5.

When equal quantities are mixed, average concentration = (40 + 50 + 60)/3 = $\frac{150}{3}$ = 50%.

Using compound growth: 100(1+r)³ = 160. (1+r)³ = 1.6. 1+r = 1.6^($\frac{1}{3}$) ≈ 1.1696. r ≈ 16.96% ≈ 16.5%.

Let n = previous innings. 40n + 65 = 45(n+1). 40n + 65 = 45n + 45. 20 = 5n. n = 4.

Total distance = 40 + 60 + 100 = 200 km. Time for first = $\frac{40}{20}$ = 2 hours. Time for second = $\frac{60}{30}$ = 2 hours. Time for third = $\frac{100}{50}$ = 2 hours. Total time = 6 hours. Average speed = $\frac{200}{6}$ = 33.33 km/h.

Let boys = 3x, girls = 2x. Total weight = (3x × 60) + (2x × 55) = 180x + 110x = 290x. Average = 290x / 5x = 58 kg.

To find the new average, we must first calculate the total score change when a student leaves and a new student joins.

Step 1: Find the Total Score of Original 5 Students

The average of 5 students is 78, so we multiply the average by the number of students to get the total.

Step 2: Calculate the New Total Score

When a student scoring 68 leaves, we subtract 68. When a new student scoring 88 joins, we add 88.

Step 3: Find the New Average

The number of students remains 5. Divide the new total by 5 to get the new average.

The new average is 82.

Answer: (B) 82

CP of 3 items at 20% profit: 3 × ($\frac{200}{1}$.2) = 500. CP of 2 items at 25% loss: 2 × ($\frac{300}{0}$.75) = 800. Total CP = 1300, Total SP = 1500. Profit% = ($\frac{200}{1300}$) × 100 = 15.$\frac{38}{3}$.58 ≈ 4.29%.

Sum of 4 numbers = 35 × 4 = 140. Sum of 3 numbers = 28 + 36 + 42 = 106. Fourth number = 140 - 106 = 34.