Class 8 Maths – Chapter 13
Direct and Inverse Proportions
STEP 3: NCERT Type Questions (Solved)

Question 1:
If the cost of 7 kg of sugar is ₹294, find the cost of 5 kg of sugar.

Solution:
Weight and cost are in Direct Proportion.

Cost of 1 kg = 294 ÷ 7 = ₹42
Cost of 5 kg = 42 × 5 = ₹210

Question 2:
12 workers can complete a work in 15 days. How many days will 20 workers take to complete the same work?

Solution:
Number of workers and days are in Inverse Proportion.

Workers × Days = Constant
12 × 15 = 180
20 × ? = 180
? = 180 ÷ 20 = 9 days

Question 3:
A car travels 120 km in 2 hours. How far will it travel in 5 hours at the same speed?

Solution:
Distance and time are in Direct Proportion.

Distance in 1 hour = 120 ÷ 2 = 60 km
Distance in 5 hours = 60 × 5 = 300 km

Question 4:
8 taps can fill a tank in 6 hours. How many taps are required to fill the tank in 4 hours?

Solution:
Number of taps and time are in Inverse Proportion.

Taps × Time = Constant
8 × 6 = 48
? × 4 = 48
? = 48 ÷ 4 = 12 taps

📝 NCERT Exam Tip:
Always mention:
• Type of proportion
• Formula used
• Final answer with unit