IBPS RRB Officer Prelims 14 Nov 2016 Shift 1 Paper

(1) Let speed of boat in stillwater be x kmph.
∴ Rate downstream
= (x + 4) kmph
Rate upstream
= (x – 4) kmph
Distance covered downstreamin 6 hours
= 6 (x + 4) km.
Distance covered upstream in
5 hours = 5 (x – 4) km.
According to the question,
2×5(x–4)=6(x+4)
⇒10x–40=6x+24
⇒10x–6x=40+24
⇒4x=64
⇒x=

64

4

=16 kmph