Checking proportions and finding a missing term: Class 6 practice
Four numbers a, b, c, d are in proportion (a : b :: c : d) if a × d = b × c (product of extremes = product of means). Read the method, follow the three worked examples, then try the six questions.
What you should know first
- Ratios
The idea behind checking proportions and finding a missing term
Four numbers a, b, c, d are in proportion (a : b :: c : d) if a × d = b × c (product of extremes = product of means). Use this to test a proportion or find a missing term.
Step-by-step method
- Multiply the extremes (first and last).
- Multiply the means (middle two).
- Equal products mean they are in proportion; solve for a missing term.
Worked example 1 (Basic)
Are 6, 6, 36, 36 in proportion?
- Extremes 6 × 36 = 216
- Means 6 × 36 = 216
- Answer: Yes
Worked example 2 (Standard)
Find x if 6 : 8 :: 12 : x.
- 6x = 8 × 12
- x = 16
- Answer: 16
Worked example 3 (Challenge)
10 notebooks cost ₹600. Using proportion, find the cost of 30 notebooks.
- 10 : 30 :: 600 : x
- x = 1800
- Answer: ₹1800
Common mistakes and misconceptions
- Multiplying the wrong pair
- Not simplifying ratios before comparing
Practice questions
- (Basic) Are 2, 10, 8, 40 in proportion?
- (Basic) Are 9, 9, 54, 55 in proportion?
- (Standard) Find x if 4 : 8 :: 8 : x.
- (Standard) Find x if 2 : 7 :: 4 : x.
- (Challenge) 7 notebooks cost ₹350. Using proportion, find the cost of 21 notebooks.
- (Challenge) 5 notebooks cost ₹275. Using proportion, find the cost of 30 notebooks.
Answer key with full working
- Q1: Extremes 2 × 40 = 80 → Means 10 × 8 = 80 → Answer: Yes
- Q2: Extremes 9 × 55 = 495 → Means 9 × 54 = 486 → Answer: No
- Q3: 4x = 8 × 8 → x = 16 → Answer: 16
- Q4: 2x = 7 × 4 → x = 14 → Answer: 14
- Q5: 7 : 21 :: 350 : x → x = 1050 → Answer: ₹1050
- Q6: 5 : 30 :: 275 : x → x = 1650 → Answer: ₹1650
Syllabus note
This skill is listed under "Ratio and Proportion" for Class 6 in the NCERT/CBSE books. ICSE, IGCSE, IB and state boards may teach it in a different chapter or year.
Answers on this page are generated and automatically re-checked by a second, independent calculation. They have not been reviewed by a teacher — if you spot a problem, tell us on WhatsApp.
Related practice and notes
Frequently asked questions
Which chapter is checking proportions and finding a missing term in?
"Ratio and Proportion", Class 6 Maths (NCERT/CBSE). Other boards may place it differently.
How were the answers checked?
Answers on this page are generated and automatically re-checked by a second, independent calculation. They have not been reviewed by a teacher — if you spot a problem, tell us on WhatsApp.