Question : The speed of a boat in still water is 15 km/hr, and the speed of the current is 5 km/hr. In how much time (in hours) will the boat travel a distance of 60 km upstream and the same distance downstream?
Option 1: 20
Option 2: 12
Option 3: 9
Option 4: 10
Correct Answer: 9
Solution :
Given, The speed of a boat in still water is 15 km/hr The speed of the current is 5 km/hr Distance of upstream or downstream = 60 km We know, $\text{Time} = \frac{\text{Distance}}{\text{Speed}}$ Also, If the speed of the boat is $x$ km/hr, and the speed of the stream is $y$ km/hr then, Speed of boat upstream = $(x - y)$ km/hr Speed of boat downstream = $(x + y)$ km/hr According to the question: ⇒ $\frac{D}{(x - y)} + \frac{D}{(x +y)} = T$ ⇒ $\frac{60}{15 - 5} + \frac{60}{15 + 5} = T$ ⇒ $T = \frac{60}{10} + \frac{60}{20}$ ⇒ $T = 6 + 3$ ⇒ $T = 9$ hours Hence, the correct answer is 9.
Application | Eligibility | Selection Process | Result | Cutoff | Admit Card | Preparation Tips
Question : A boat running downstream covers a distance of 20 km in 2 hours, while it covers the same distance upstream in 5 hours. Then, the speed of the boat in still water is:
Question : A boat covers a distance of 72 km downstream in 6 hours, while it takes 12 hours to cover the same distance upstream. What is the speed of the boat in still water?
Question : A boat travels 60 kilometres downstream and 20 kilometres upstream in 4 hours. The same boat travels 40 kilometres downstream and 40 kilometres upstream in 6 hours. What is the speed (in km/hr) of the stream?
Question : A boat can go 40 km downstream and 25 km upstream in 7 hours 30 minutes. It can go 48 km downstream and 36 km upstream in 10 hours. What is the speed (in km/hr) of the boat in still water?
Question : A boat takes 4 hours to travel from a place X to Y downstream and back from Y to X upstream. If the distance from X to Y is 10.5 km, and the speed of the current is 9 km/hr, then the speed of the boat in still water, in km/hr, is:
Regular exam updates, QnA, Predictors, College Applications & E-books now on your Mobile