NCERT Solutions Ganita Prakash (Part 1) Chapter 7 .2 Ratios · 7.3 Ratios in their Simplest Form — In-text Questions
Book page 1617 Updated on2026-09-05
Q1.
By what factor should we multiply the ratio 60 : 40 (image A) to get 90 : 60 (image D)?
Answer
By the factor 3⁄2, applied to both terms.
60 × 3⁄2 : 40 × 3⁄2 = 90 : 60
Why multiply both terms: A ratio is not two separate numbers; it is a comparison. If only one term is multiplied the comparison itself changes. Multiplying both terms by the same factor leaves the comparison untouched — exactly as multiplying the numerator and the denominator of a fraction by the same number gives an equivalent fraction.
Q2.
What is the simplest form of the ratios of images B and E?
Neither of these is 3 : 2, so the ratios of B and E are not proportional to those of A, C and D — which is the arithmetic behind what your eye already noticed.
Tip: Dividing by any common factor moves you towards the simplest form, but only dividing by the HCF gets you there in one step. 40 : 20 divided by 4 is 10 : 5, which is correct but not yet simplest.