alleryStart learning →Convert a speed of $90$ km/hr into metres per second.
- $18$ m/s
- $22.5$ m/s
- $25$ m/s
- $27$ m/s
Show answer and solution
Correct answer: C. $25$ m/s
Multiply km/hr by $\dfrac{5}{18}$: $90 \times \dfrac{5}{18} = 25$ m/s.
RRB JE Boats and Streams — practice questions
Explore 38 free Boats and Streams questions in RRB JE Quantitative Aptitude. Open each question or exercise to read its content, reference answers and available explanation.
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Showing questions 1–30 of 38.
Convert a speed of $90$ km/hr into metres per second.Read the answer and worked solution →A car covers $360$ km in $4$ hours. Find its average speed.Read the answer and worked solution →A man travels the first half of a journey at $30$ km/hr and the second half at $60$ km/hr. Find his average speed for the whole journey.Read the answer and worked solution →If the ratio of the speeds of A and B is $3 : 4$, what is the ratio of the times they take to cover the same distance?Read the answer and worked solution →Key in the percentage answersRead the answer and worked solution →Complete the discount formulaRead the answer and worked solution →Money maths bingoRead the answer and worked solution →Pick the money term, fastRead the answer and worked solution →Onto the bill, or off it?Read the answer and worked solution →Tap the wrong word about moneyRead the answer and worked solution →Complete the idea of a percentageRead the answer and worked solution →Ratios into percentagesRead the answer and worked solution →Order the steps of the unitary methodRead the answer and worked solution →What is the percentage taken OF?Read the answer and worked solution →True or false: percentages and their baseRead the answer and worked solution →Match each comparison to its formRead the answer and worked solution →Common percentage conversionsRead the answer and worked solution →Assertion and reasonRead the answer and worked solution →Two are true, one is notRead the answer and worked solution →Three of these are wrong. Find the one that holds.Read the answer and worked solution →Tap every correct way to express one quarterRead the answer and worked solution →Flip and pair: fraction with percentageRead the answer and worked solution →Spot the one that does not belongRead the answer and worked solution →True or false: the unitary methodRead the answer and worked solution →Ratio, fraction, or percentage?Read the answer and worked solution →Complete the comparison chainRead the answer and worked solution →Percentage of a quantityRead the answer and worked solution →Order the steps: turn a part into a percentageRead the answer and worked solution →Assertion and reason: comparisonsRead the answer and worked solution →For a fixed distance, if the speed is increased then the time taken:Read the answer and worked solution →
Worked practice questions
A car covers $360$ km in $4$ hours. Find its average speed.
- $60$ km/hr
- $80$ km/hr
- $90$ km/hr
- $100$ km/hr
Show answer and solution
Correct answer: C. $90$ km/hr
Speed $= \dfrac{\text{Distance}}{\text{Time}} = \dfrac{360}{4} = 90$ km/hr.
A man travels the first half of a journey at $30$ km/hr and the second half at $60$ km/hr. Find his average speed for the whole journey.
- $35$ km/hr
- $40$ km/hr
- $45$ km/hr
- $50$ km/hr
Show answer and solution
Correct answer: B. $40$ km/hr
For equal distances, average speed is the harmonic mean: $\dfrac{2xy}{x+y} = \dfrac{2 \times 30 \times 60}{90} = \dfrac{3600}{90} = 40$ km/hr.
Not the arithmetic mean $(30 + 60)/2 = 45$ — that holds for equal *times*, not equal *distances*.
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