Question

What is the swimming speed of the champion swimmer in the still water of a river?
Statement 1: The swimmer seems at the speed of 3 km per hour upstream.
Statement 2: The swimmer swims at the speed of 5 km per hour downstream.

• A. If statement 1 alone is sufficient to answer
• B. If statement 2 alone is sufficient to answer
• C. If both the statements are needed to answer
• D. Cannot answer from both statements using together

Hint:

When solving problems related to speed in still water, always use the relationship between upstream and downstream speeds to find the speed in still water.

Answer 1

The Correct Option is C

To find the swimmer's speed in still water, we need to understand the relationship between the swimmer's upstream and downstream speeds. The swimming speed in still water can be calculated using the formula: \[ \text{Speed in still water} = \frac{\text{Upstream speed} + \text{Downstream speed}}{2} \] Step 1: Analyze Statement 1.
Statement 1 gives the swimmer's speed upstream as 3 km/h. However, we also need to know the downstream speed to calculate the speed in still water, so Statement 1 alone is insufficient. Step 2: Analyze Statement 2.
Statement 2 gives the swimmer's speed downstream as 5 km/h. Again, we need the upstream speed to calculate the speed in still water, so Statement 2 alone is also insufficient. Step 3: Use both statements together.
By combining both statements, we have the upstream speed (3 km/h) and the downstream speed (5 km/h). Using the formula: \[ \text{Speed in still water} = \frac{3 + 5}{2} = 4 \, \text{km/h}. \] Thus, both statements are needed to answer the question. Step 4: Conclusion.
Therefore, the correct answer is option (3): Both the statements are needed to answer the question.