RRB NTPC 17 January 2017 Paper

(1) Distance travelled by car in 10minutes = $\frac{10}{60}\times 20=\frac{10}{3}$ km
i.e. the distance between two car is = $\frac{10}{3}$ km
Let the speed of the woman be xkm/hr The woman will cover $\frac{10}{3}$ k min 8 minutes with (20+x)km/hr relative speed
∴ $\left(20+\mathit{x}\right)\frac{8}{60}=\frac{10}{3}$ (∵ d = st)
⇒$\left(20+\mathit{x}\right)=\frac{200}{8}$
x = 5 km/hr