Question

Ex.1. A man rows down a river 15 km in 3 hrs. with the stream and returns in 7 hrs, The rate at which he rows in still water is SSC CGL (Tier-1) 2013 (1) 2.5 km/hr (2) 1.5 km/hr (3) 3.5 km/hr (4) 4.5 km/hr

11th - 12th Class

Maths

Solution

114

4.0 (1 ratings)

mathrm{Sol. } ~ ( 3 ) ~ L e t ~ s p e e d ~ o f ~ p e r s o n ~ i n ~ s t i l l ~ w a t e r ~ ( =x ) kmph and speed of current ( =y ) kmph Now, According to the question, ( therefore x+y=frac{15}{3}=5 mathrm{kmph} ) (i) ( x-y=frac{15}{frac{15}{2}}=2 mathrm{kmph} ) (ii) On adding eq (i) & (ii), ( 2 x=7 Rightarrow x=frac{7}{2}=3.5 mathrm{kmph} )