📄 01 - SET-1 (TDS problems) Part 1, p.13

⭐ Basic Concepts

📌 Average Speed Question Pattern

• Average Speed Questions are often given in parts like different Speeds/Distances/Times for each part, and we must calculate each part separately.

⚡Average Speed Formula 1:

• Average Speed formula that works only when the Distances are the same but the Speeds are different. (For cases when traveling from points A→B and from B→A).
• Here x and y denote two different Speeds.

⚡Average Speed Formula 2:

• Average Speed formula that works for all cases.
• When solving Average Speed type problems using this formula, always start the sum from the denominator by placing each Time value in the denominator, and then place the corresponding Distance value for each Time value in the numerator.

🎯 Problem 11:

The speed of a car is 90 kmph in the first hour and 60 kmph in the second hour. What is the average speed of the car?

A) 72
B) 75
C) 30
D) 80

• The question explicitly specifies the time duration and speed for each part of the journey, so we can simply add those time values to get the total time value.

🎯 Problem 12:

A biker rides from Pondicherry to Chennai at 40 kmph and returns from Chennai to Pondy at 60 kmph. Find the average speed of the whole journey.

A) 50
B) 100
C) 48
D) 60

🎯 Problem 13:

One-fourth of a certain journey is traveled at 5 kmph and the remaining distance at 10 kmph. What is the average speed of the whole journey in kmph?

A) 7.5
B) 8
C) 15
D) NOTA