A person travels 30% of the distance at 85 kmph and the rest at 35 kmph. This is used to calculate:

AIIMS CRE, SNO-2024

Non Nursing Subjects

Medium

Appeared in: AIIMS CRE, SNO-2024

Explanation

The problem provides speeds for different segments of a total distance, which is the classic setup for calculating average speed.
Average speed is defined as Total Distance divided by Total Time.
To find the total time, the time for each segment is calculated (Time = Distance/Speed) and then added together.
Let the total distance be 'D'. The time for the first segment is (0.30 * D) / 85, and for the second is (0.70 * D) / 35.
When you compute the average speed (D / Total Time), the variable 'D' cancels out, allowing you to find a specific numerical value for the average speed.

Option A: The maximum speed is explicitly stated in the problem as 85 kmph. It is a given piece of information, not the result of a calculation involving all the provided data.
Option C: Acceleration is the rate of change of velocity. The problem describes travel at constant speeds for two different segments. There is no information about how the speed changes between these segments, so acceleration cannot be calculated.
Option D: To calculate the total time in hours, the total distance in kilometers must be known. Since the problem only gives percentages of an unknown total distance, a specific numerical value for the total time cannot be determined.

Visual 1: Flowchart: 'Calculating Average Speed'. Step 1: Define total distance as 'D'. Step 2: Calculate time for segment 1 (t1 = 0.3D / 85). Step 3: Calculate time for segment 2 (t2 = 0.7D / 35). Step 4: Calculate total time (T = t1 + t2). Step 5: Calculate average speed (Avg. Speed = D / T). This visual clarifies how the unknown distance 'D' cancels out.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Calculation of average speed when different parts of a journey are covered at different speeds as background academic context rather than a clinical decision trigger.
This question tests quantitative aptitude and problem-solving skills, which are essential for nurses.
Nurses frequently perform calculations for drug dosages, IV drip rates, and fluid balance, which require similar logical and mathematical reasoning.
What if the question provided the total time taken for the journey instead of the speeds? In that case, you could calculate the total distance, but not necessarily the average speed without more information.

How to Approach the Question

First, identify all the information given: a percentage of distance (30%) at a specific speed (85 kmph), and the remaining distance (70%) at another speed (35 kmph).
Understand the core question: What can be calculated using all this information combined?
Evaluate each option based on standard physics formulas.
For 'Average speed', recall the formula: Total Distance / Total Time. Set up the equation using a variable 'D' for distance. Notice that 'D' will cancel out, meaning a definite value can be found.
For 'Maximum speed', recognize this is a value given directly in the problem, not a calculation.
For 'Acceleration', recall it requires a change in velocity over time. The problem gives constant speeds, not changing velocity.

Concept Tested & Keywords

Concept Tested: Calculation of average speed when different parts of a journey are covered at different speeds.
Stem keywords: travels, 30% of the distance, 85 kmph, rest, 35 kmph
Lead-in keywords: calculate

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