Solution:Distance covered by both men in first hour = 4 + 2 = 6kmDistance covered by both men in second hour = 4 + 2.5 = 6.5km
Distance covered by both men in third hour = 4 + 3 = 7km
Total distance = 6 + 6.5 + 7 ....... t (Times)
72 = t/2 [2 × 6 + (t - 1) × 0.5]
⇒ 144 = t[12 + 0.5t - 0.5]
⇒ 144= 11.5t + 0.5t2
⇒ t2 + 23t - 288 = 0
⇒ t² + 32t - 9t - 288 = 0
⇒ t(t + 32) - 9(t + 32) = 0
⇒ t = 9 hours
Distance covered by first man in 9 hours from Point A = 4 × 9 = 36km
∴ The two men will meet at midway between A and B