Question

Two cars started at same time, same place and towards same direction. First car goes at a speed of 5km/hr in first and 7 km/hr in second hour and repeats the cycle over the entire journey. Similarly second car goes at 4km/hr in first hour and 9km/hr in second hour and repeats the cycle over the entire journey.Then these two cars for the first time for after how many hours of journey?

Answer 1

Answer:

After 1.5 hrs of journey both car meet for first time

Step-by-step explanation:

in 1st Hr

First Car goes 5 km

Second Car goes 4 km

=> First Car is ahead of second Car

then in 2nd hour

First car goes 7 km  hence in total 2 hrs

First car goes = 5 + 7 = 12 km

Second Car goes 9 km hence in total 2 hrs

Second Car goes = 4 + 9 = 13 km

=> Second Car is ahead of first Car

after 1 hr First car was ahead and after 2nd hour Second car is ahead

=> Car meet  between 1st & 2nd Hour

After 1 hr  First car was ahead 1 km of second Car

let say Car meet after x hour of 1 hr

=> in x hr second car travel 1 km more than First Car

Distance traveled by second car in x hr  = 9x

Distance traveled by First car in x hr  = 7x

=> 9x - 7x = 1

=> 2x = 1

=> x = 1/2

1 + 1/2 = 3/2  hr  = 1.5 hr  - 1 hr 30 mins

After 1.5 hrs of journey both car meet for first time

and this cycle will keep repeating every 1.5 hr