Question

Amit and rahul are 20km apart they bike towards eachother amit speed being thrice rahuls ,the distance between them decrease at the rate of 1km/min .After 5 minutes

Answer 1

Given :

The distance between Amit and Rahul = d = 20 km

The speed of Amit = 3 × speed of Rahul

The rate of distance decrease between them = 1 km/min

To Find :

The distance between them after 5 minutes

Solution :

Let The speed of Rahul = S km/min

The speed of Amit = 3 S  km/min

Let The distance between them after 5 min = D km

According to question

Distance between them after t min = Initial distance between them × $(1-\dfrac{rate}{100})^{time}$

Or,   D = d × $(1-\dfrac{r}{100})^{t}$

Or, D = 20 km × $(1-\dfrac{1}{100})^{5}$

Or, D = 20 km × $(0.99)^{5}$

∴ D = 20 km × 0.9509

i.e Distance = 19.019 km

Hence, The distance between them after 5 min is  19 km and 19 m   Answer