7.2 Applying percentage change to an existing ratio

Example 41: Two numbers are in the ratio 3 : 4. If the first number is increased by 25% and the second is decreased by 20%, find the new ratio. New first number = 3 × 1.25 = 3.75 New second number = 4 × 0.8 = 3.2 New ratio = 3.75 : 3.2 = 375 : 320 = 75 : 64 (dividing by 5).

Example 42: The ratio of two numbers is 3 : 4 and their sum is 700. If the sum is increased by 40% while the ratio is kept the same, find the new two numbers. New sum = 700 × 1.4 = 980. Ratio 3:4, total parts = 7. 1 part = 980/7 = 140. New numbers = 3×140 : 4×140 = 420 and 560.