the current of stream runs at kmph a motor boat goes..., Problems On Boats & Streams, General Mathematics

Question:The current of stream runs at kmph. A motor boat goes `35` km upstream and back again to the starting point in `12` hours. The speed of the motor boat in still water is :

A `6 km∕hr` 
B `7 km∕hr` 
C `8 km∕hr` 
D `8.5 km∕hr`

/14

+ AnswerA

+ ExplanationLet the speed in still water be x kmph

Then, speed upstream 

`= (x - 1) kmph,

speed downstream 

`= (x + 1) kmph`

`:. 35/(x - 1) + 35/(x + 1) = 12`

`⇔ 6x^2 - 35x - 6 = 0`

`:. (x - 6) (6x + 1) = 0`

`or x = 6.`

Hence, the speed in still water `= 6 kmph.`

+ Report

Descriptive on Problems On Boats & Streams Ebook

Total Preview: 702