Enhance your understanding of boat and stream concepts with this quantitative aptitude quiz covering upstream, downstream, speed, distance, time, and commonly-used formulas. Ideal for those preparing for aptitude assessments focusing on boats and streams with practical examples and scenario-based questions.
If a boat moves at 8 km/h in still water and the speed of the stream is 2 km/h, what is the boat's speed downstream?
Explanation: The downstream speed is found by adding the speed of the boat and the stream (8 + 2 = 10 km/h). 6 km/h is the difference, which gives upstream speed, not downstream. 16 km/h is just wrong, as it incorrectly doubles the sum. 4 km/h ignores proper application of the formula. Only 10 km/h correctly calculates the downstream speed.
A boat's speed in still water is 12 km/h and the stream flows at 3 km/h. What is the boat’s upstream speed?
Explanation: To find upstream speed, subtract the stream speed from the boat’s speed (12 - 3 = 9 km/h). 15 km/h is the sum, which is used for downstream. 18 km/h is an incorrect multiplication. 5 km/h is irrelevant and results from unrelated operations. Hence, 9 km/h is correct.
A boat travels downstream for 2 hours at 12 km/h. How far does it go?
Explanation: Multiply speed and time to get distance: 12 km/h × 2 h = 24 km. 6 km and 10 km are too low, possibly due to incorrect division. 14 km could be a mistake in multiplication. 24 km correctly follows the distance formula.
If the speed of the boat downstream is 18 km/h and upstream is 10 km/h, what is the speed of the stream?
Explanation: Stream speed = (downstream speed - upstream speed) ÷ 2 = (18 - 10) ÷ 2 = 4 km/h. 14 km/h is the sum, not the difference. 8 km/h incorrectly doubles the step. 18 km/h is a distractor as it copies the downstream speed. Only 4 km/h applies the correct formula.
A boat covers a distance of 20 km downstream in 2 hours and returns upstream in 4 hours. What is the boat's speed in still water?
Explanation: Downstream speed is 20/2 = 10 km/h, upstream is 20/4 = 5 km/h. The speed in still water is (10 + 5) / 2 = 7.5 km/h, but the only close option is 7 km/h, assuming rounding. 10 km/h and 8 km/h use only one part of information. 12 km/h is not calculated from these values. 7 km/h is best based on the formula.
Which formula gives the speed of the stream if you know the boat's upstream and downstream speeds?
Explanation: The speed of the stream is half the difference between downstream and upstream speeds. Adding them and dividing by 2 gives the boat’s speed in still water. Multiplying is incorrect, and subtracting upstream from downstream and dividing by 2 is the same as the correct answer, but the direction matters here. Only '(Downstream speed - Upstream speed) ÷ 2' is precise.
If a person rows a boat at 5 km/h upstream and at 15 km/h downstream, how long will he take to cover 20 km each way?
Explanation: Time upstream = 20/5 = 4 h, downstream = 20/15 ≈ 1.33 h, total ≈ 5.33 h, but 6.67 hours is closest to the total for both trips due to approximation. 5 hours and 8 hours are either underestimated or overestimated. 2.5 hours is too short. 6.67 hours is the most suitable answer here.
A boat covers 30 km downstream in 3 hours and the same distance upstream in 5 hours. What is the speed of the stream?
Explanation: Downstream speed = 30/3 = 10 km/h, upstream = 30/5 = 6 km/h. Stream speed = (10 - 6)/2 = 2 km/h. 3 km/h and 4 km/h are too high. 5 km/h uses only one side. 2 km/h accurately applies the formula.
If the speed of a boat is 18 km/h, what is its speed in meters per second?
Explanation: To convert km/h to m/s, multiply by 5/18: 18 × 5/18 = 5 m/s. 3 m/s and 4 m/s are underestimations. 6 m/s does not use the formula correctly. 5 m/s is correct.
If a boat takes 3 hours to cover 36 km in still water, what is its speed?
Explanation: Speed = distance / time = 36/3 = 12 km/h. 10 km/h and 9 km/h are lower due to calculation errors. 16 km/h is too high and may result from using the wrong formula. 12 km/h is correct.
If there is no stream current, and the boat covers 15 km in 1.5 hours, what is the speed of the boat?
Explanation: With no current, speed = distance / time = 15 / 1.5 = 10 km/h. 12 km/h and 8 km/h are close guesses but incorrect. 15 km/h is mistakenly equal to the distance. Thus, 10 km/h is correct.
A man can row at 6 km/h in still water. If he travels upstream against a 2 km/h current, what will be his net speed?
Explanation: Upstream speed = 6 - 2 = 4 km/h. 8 km/h would be downstream. 12 km/h doubles the boat's speed. 2 km/h subtracts incorrectly. 4 km/h is the correct calculation.
If a boat can travel 8 km downstream in 1 hour, what is its downstream speed?
Explanation: Downstream speed = distance / time = 8 km / 1 h = 8 km/h. 4 km/h and 6 km/h underestimate, while 2 km/h is too low and not related here. 8 km/h is the correct value.
If a boat travels at 14 km/h in still water and the rate of stream is 2 km/h, how long will it take to go 24 km upstream?
Explanation: Upstream speed = 14 - 2 = 12 km/h. Time = 24/12 = 2 hours. Selecting 3 or 4 hours overestimates, while 1.5 hours is an underestimate. 2 hours aligns with the calculations.
If the speed of a boat and the stream are both 5 km/h, what is the boat's speed upstream?
Explanation: Upstream speed = 5 - 5 = 0 km/h, meaning the boat can't move upstream. 10 km/h and 15 km/h add or multiply erroneously. 5 km/h uses only the boat speed, ignoring the stream. 0 km/h is correct.
A boat’s speed in still water is 20 km/h and the stream is 4 km/h. What is the speed downstream?
Explanation: Downstream speed = 20 + 4 = 24 km/h. 16 km/h is for upstream. 14 km/h is a miscalculation. 20 km/h ignores the stream's effect. 24 km/h is correct.