Class 7 Ratios and Percentages — practice questions with answers
Comparing Quantities · 5 sample questions from the school syllabus. Try each one, then open the answer and the worked solution.
1. Write the ratio 12 : 18 in its simplest form.
A2 : 3
B3 : 2
C6 : 9
D4 : 6
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Answer: A) 2 : 3
Divide both terms by the HCF 6: 612 = 2 and 618 = 3, so 12 : 18 = 2 : 3.
2. What is 20% of 150?
A27
B30
C60
D33
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Answer: B) 30
20% of 150 = 10020 x 150 = 30.
3. In Riya's piggy bank there are ₹1 and ₹2 coins in the ratio 3 : 2. There are 30 coins in total. How many ₹2 coins are there?
A13
B12
C11
D24
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Answer: B) 12
Total parts = 3 + 2 = 5, each part = 530 = 6 coins. The ₹2 coins are 2 parts = 2 x 6 = 12.
4. A water tank is 40% full. When 30 litres more water is added, it becomes 70% full. What is the full capacity of the tank in litres?
A110
B200
C90
D100
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Answer: D) 100
The 30 litres added corresponds to 70% - 40% = 30% of the capacity. So 30% of capacity = 30 litres, capacity = 30 x 100/30 = 100 litres.
5. In a school, the ratio of girls to boys is 3 : 2. If 60% of the girls and 50% of the boys travel by bus, what percentage of all the students travel by bus?
A56%
B55%
C60%
D50%
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Answer: A) 56%
Take 5 parts total: girls = 3, boys = 2. Bus travellers = 60% of 3 + 50% of 2 = 1.8 + 1.0 = 2.8 out of 5 = 52.8 = 56%.