📘 Cognitive Practice Set – 1
These aptitude Questions will help you to prepare for the Cognitive Section of the Mahindra placement Exam.
Q1: A lady went to the market with a few Rs 1 notes and a few 20-paise coins. When she returned, she had as many Rs 1 notes as she originally had 20-paise coins and vice versa. She actually came back with about one-third of what she had gone with. How much did she spend in the market?
- A. Rs 14.40
- B. Rs 14.70
- C. Rs 15.50
- D. Rs 17.40
After switch: y + 0.2x = 1/3(x + 0.2y).
3(y + 0.2x) = x + 0.2y
3y + 0.6x = x + 0.2y
2.8y = 0.4x
7y = x
If x = 21, y = 3 → Original amount = Rs 21.60, Final = Rs 7.20 → Spent = Rs 14.40
Q2: If the ratio of A to B is 3:4 and B to C is 2:5, what is the ratio A:B:C?
- A. 3:4:5
- B. 3:4:10
- C. 6:8:20
- D. 15:20:25
To make B the same in both ratios, multiply first ratio by 2: A:B = 6:8
And multiply second ratio by 4: B:C = 8:20
Therefore, A:B:C = 6:8:20 (which simplifies to 3:4:10)
Q3: The positions of the first and the fifth digits of the number 81943275 are interchanged. Similarly, the positions of the second and the sixth digits are interchanged, and so on. Which of the following will be the third digit from the right end after the rearrangement?
- A. 9
- B. 8
- C. 2
- D. 1
After interchanging:
1st↔5th (8↔3), 2nd↔6th (1↔2), 3rd↔7th (9↔7), 4th↔8th (4↔5)
New number: 3 2 7 5 8 1 9 4
3rd digit from right end = 1
Q4: The sum of four consecutive odd numbers is 208. Find the smallest number.
- A. 49
- B. 51
- C. 53
- D. 55
4x = 196 → x = 49
The four consecutive odd numbers are 49, 51, 53, and 55
Q5: If a number is divided by 5, the remainder is 3. What will be the remainder when the square of the number is divided by 5?
- A. 1
- B. 2
- C. 3
- D. 4
(5k + 3)² = 25k² + 30k + 9
When divided by 5, remainder = 9 mod 5 = 4
Q6: The average weight of a group of 20 boys was calculated to be 89.4 kg, but one weight was misread as 78 kg instead of 87 kg. What is the correct average weight?
- A. 88.95 kg
- B. 89.25 kg
- C. 89.55 kg
- D. 89.85 kg
Original sum = 20 × 89.4 = 1788 kg
Corrected sum = 1788 + 9 = 1797 kg
New average = 1797 ÷ 20 = 89.85 kg
Q7: A train 150 meters long takes 18 seconds to cross a platform 180 meters long. What is its speed?
- A. 60 km/h
- B. 66 km/h
- C. 72 km/h
- D. 90 km/h
Speed = 330 ÷ 18 = 18.33 m/s
Converting to km/h: 18.33 × 3.6 = 66 km/h
Q8: A person saves 10% of his income. If his income increases by 20% and expenses by 15%, what is the new savings percentage?
- A. 11%
- B. 12.5%
- C. 13.75%
- D. 14%
New income = 120, new expenses = 90 × 1.15 = 103.5
New savings = 120 – 103.5 = 16.5
New savings percentage = 16.5 ÷ 120 × 100 = 13.75%
Q9: A number when divided by 7 leaves a remainder 5. What remainder will it leave when divided by 14?
- A. 3
- B. 5
- C. 12
- D. Cannot be determined
When k is even (e.g., k=0), number = 5, remainder when divided by 14 = 5
When k is odd (e.g., k=1), number = 12, remainder when divided by 14 = 12
Since we don’t know if k is even or odd, the remainder cannot be determined uniquely.
Q10: A clock is set right at 6 a.m. The clock loses 10 minutes in every 24 hours. What will be the time shown when the clock shows 6 a.m. on the 4th day?
- A. 5:50 a.m.
- B. 5:30 a.m.
- C. 5:40 a.m.
- D. 5:20 a.m.
Clock loses 10 min/day, so after 3 days it’s 30 min slow.
When clock shows 6:00 a.m., the actual time is 6:00 + 0:30 = 6:30 a.m.
However, the question appears to be asking the reverse: what does the clock show when the actual time is 6:00 a.m.?
If actual time is 6:00 a.m., clock will show 5:30 a.m.