2017 · Q70
Two men set out at the same time to walk toward each other from points A and B; 72 km apart. The first man walks at the speed of 4 kmph while the second walks 2 km in the first hour, 2 km in the second hour, 3 km in the third hour, and so on. The two men will meet
general-mental-abilityquantitative-aptitude
- Ain 8 hours
- Bnearer to A than B
- Cnearer to B than A
- Dmidway between A and B
Explanation
The second man’s hourly distances form the arithmetic progression 2, 2½, 3, … km (as in the original paper and reputable solved versions), while the first man walks 4 km every hour. Together they cover 6, 6.5, 7, … km per hour – an AP with a = 6 and d = 0.5. Solving t/2 × [12 + 0.5(t−1)] = 72 gives t = 9 hours, in which the first man walks 4 × 9 = 36 km – exactly half of 72 km. Hence they meet midway between the stations, giving (D).