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Direct and Inverse Proportions — Class 8 CBSE Mathematics MCQs with Solutions
Free Class 8 CBSE Mathematics Direct and Inverse Proportions MCQs with step-by-step solutions. Practise online on Prepizo — no login needed.
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Sample questions with solutions
Q1 — easy
If 4 workers finish a job in 12 days, 8 workers will take:
A. 3 days
B. 6 days ✓ Correct
C. 16 days
D. 24 days
Solution: More workers, fewer days — inverse proportion.
Q2 — easy
A car travels 60 km in 1 hour. How far in 3 hours at the same speed?
A. 120 km
B. 150 km
C. 180 km ✓ Correct
D. 200 km
Solution: 60 × 3 = 180 km.
Q3 — easy
Which pair is in inverse proportion?
A. distance and time at fixed speed
B. speed and time for a fixed distance ✓ Correct
C. cost and number of items
D. side and perimeter of a square
Solution: For a fixed distance, higher speed means less time.
Q4 — hard
If x and y are in inverse proportion and x = 8 when y = 15, find y when x = 12.
A. 8
B. 10 ✓ Correct
C. 12
D. 20
Solution: xy = 120, so y = 120/12 = 10.
Q5 — hard
A contractor uses 12 machines for 9 days. If 3 machines break down, how long will the rest take?
A. 10 days
B. 11 days
C. 12 days ✓ Correct
D. 15 days
Solution: 12 × 9 = 9 × d → d = 12.
Q6 — hard
Cost of 8 m cloth is ₹1200. How much cloth can be bought for ₹1950?
A. 11 m
B. 12 m
C. 13 m ✓ Correct
D. 15 m
Solution: ₹150 per metre; 1950/150 = 13 m.
Q7 — medium
A machine makes 300 bolts in 5 minutes. How many in 12 minutes?
A. 600
B. 660
C. 720 ✓ Correct
D. 780
Solution: 60 per minute × 12 = 720.
Q8 — medium
If 9 pipes empty a tank in 20 minutes, how many pipes empty it in 15 minutes?
A. 10
B. 11
C. 12 ✓ Correct
D. 15
Solution: 9 × 20 = n × 15 → n = 12.
Q9 — medium
A map uses a scale of 1 cm = 50 km. What distance does 7.5 cm represent?
A. 300 km
B. 350 km
C. 375 km ✓ Correct
D. 400 km
Solution: 7.5 × 50 = 375 km.