Maths:Speed

A car was travelling from Town A to Town B. At the same time, a van was travelling from town B towards Town A. After travelling for 120km, the car went past Gem market at 08:30. At 10:00, the van passed by the car at the midpoint between Gem Market and Town B. The van reached Gem Market at 12:30. Both the van and the car did not change their speeds for the entire Journey. What was the difference between the speed of the car and the van?

Solution 

A library was located between Mall P and Mall Q. Valerie and Celine left Mall P at the same time. When Valerie travelled ¼ of the distance between Mall P and the library. Celine was 2 km ahead of Valerie. Valerie took 20 min to reach the library while Celine took 32 min to reach Mall Q. Both of them did not change their speeds throughout the journey. The distance between the library and Mall Q was 23km. Find Celine’s speed.

Solution

When Valerie is reaching 1/4 of the distance between library and Mall P, Celine is 2km ahead of her. 

So, when Valerie reaches the library, Celine will be 8km past the library. 

When it is 20 mins

  •  Valerie will reach the library.
  • Celine will be 8km past the library. She is 15km (23 – 8) from Mall Q. 

Celine reaches Mall Q in 32 mins. So, Celine covers this distance 15km in 12mins (32 – 20)

Celine speed = 15 km / 12 mins = 15 / 0.2hr  = 75 km/hr.