Question
Anita goes to College at 20 km/h and reaches college 4 minutes late. Next time she goes at 25 km/h and reaches the college 2 minutes earlier than the scheduled time. What is the distance of her school?
A. 12 km
B. 16 km
C. 10 km
D. 15 km
Answer: C
Solution:
Speed = Distance/ time
The distance is common here. So let’s equate the distances.
Case of going late
D = 20 * (T + 4 / 60) ——- Equation 1
Case of going early
D = 25 * (T – 2 / 60) ——-Equation 2
Equating the Distances,
20 * (T + 4 / 60) = 25 * (T – 2 / 60)
20T + 80 / 60 = 25T – 50 / 60
130 / 60 = 5T
T = 130 / (60 * 5) = 13 / 30
Now, let’s calculate the distance from Equation 1.
D = 20 * (13 / 30 + 4 / 60) = 20 * (26 / 60 + 4 / 60) = 20 * 30 / 60
Therefore, D = 10 km