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Question

A person takes one hour more to cover a certain distance walking at a speed of 2 km/hour compared to walking at 3 km/hour. The distance is

The correct answer is

6 km

Let's figure out the distance the person traveled using the information about their speeds and the difference in time taken.

Distance, Speed, and Time

The relationship between distance, speed, and time is a fundamental concept in motion problems. It is given by the formula:

\( \text{Distance} = \text{Speed} \times \text{Time} \)

From this formula, we can also express time as:

\( \text{Time} = \frac{\text{Distance}}{\text{Speed}} \)

Setting Up the Problem Variables

Let the unknown distance be \(d\) kilometers.

We are given two different speeds at which the person walks:

  • Speed 1 (\(S_1\)) = 2 km/hour
  • Speed 2 (\(S_2\)) = 3 km/hour

Let \(T_1\) be the time taken to cover the distance \(d\) at Speed 1, and \(T_2\) be the time taken to cover the same distance \(d\) at Speed 2.

Calculating Time Taken at Each Speed

Using the formula \( \text{Time} = \frac{\text{Distance}}{\text{Speed}} \), we can write the time taken for each speed:

  • Time taken at 2 km/hour: \( T_1 = \frac{d}{2} \) hours
  • Time taken at 3 km/hour: \( T_2 = \frac{d}{3} \) hours

Using the Time Difference Information

The problem states that the person takes one hour more to cover the distance walking at 2 km/hour compared to walking at 3 km/hour. This means the difference between the two times is 1 hour.

So, we can write the equation:

\( T_1 - T_2 = 1 \)

Substitute the expressions for \(T_1\) and \(T_2\) we found earlier:

\( \frac{d}{2} - \frac{d}{3} = 1 \)

Solving for the Distance \(d\)

Now, we need to solve this equation to find the value of \(d\).

To subtract the fractions on the left side, we need a common denominator. The least common multiple of 2 and 3 is 6.

Multiply the first term by \( \frac{3}{3} \) and the second term by \( \frac{2}{2} \):

\( \frac{d}{2} \times \frac{3}{3} - \frac{d}{3} \times \frac{2}{2} = 1 \)

\( \frac{3d}{6} - \frac{2d}{6} = 1 \)

Combine the fractions on the left side:

\( \frac{3d - 2d}{6} = 1 \)

\( \frac{d}{6} = 1 \)

To isolate \(d\), multiply both sides of the equation by 6:

\( d = 1 \times 6 \)

\( d = 6 \)

Final Distance

The distance covered is 6 kilometers.

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Important Questions from Speed Time and Distance

  1. A train travelling at a speed of 72 km/hr crosses a post in 20 seconds. If it crosses another train travelling at a speed of 54 km/hr in the same direction in 1 minute 45 seconds, then the difference in length between the two trains is

  2. Rajiv's boat can travel along the current at the 8 km/hour and against the current at the rate 6 km/hour. Find the time taken by the boat to sail 28 km in still water.

  3. Rohit and Dinesh are 64 km apart. Rohit can walk at a speed of 15 km/hr and Dinesh at the speed of 17 km/hr. In how many hours will they meet if they are travelling towards each other?

  4. Two trains running in opposite directions cross a man standing on the platform in 25 seconds and 32 seconds respectively and they cross each other in 30 seconds. The ratio of their speed is:

  5. A worker covers a distance of 81 km in 11 hours. He travels partly on foot at 4.5 km/h and partly on bicycle at 15 km/h. What is the distance covered on the cycle?

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