Question

Ram go to the office from home in his car. Usually, he covers half the distance at 40km/h and increases the speed by 10% for the remaining half. Today he reduced car speed by 10% in the second half and reached the office 30 minutes late compared to the usual time. What is the total distance between his home and office?
1. 99 km
2. 102 km
3. 198 km
4. 204 km

Answer 1

Correct Answer - Option 3 : 198 km

Calculation:

Let d be the total distance,

Time = {(d/2)/40} + {(d/2)/(1.1 × 40)}

⇒ t = (d/80) + (d/88)      ----(I)

Today he reduced speed by 10%,

⇒ t_new = {(d/2)/40} + {(d/2)/(0.9 × 40)}

⇒ t + 0.5 = (d/80) + (d/72)      ----(II)

Equation (II) – (I) gives,

⇒ (d/72) - (d/88) = 0.5

⇒ d = 198 km

∴ Total distance between his home and office is 198 km.