.A length, originally 9cm, is increased so that the ratio of the new length to the old length is 13:3. What is the new length

The new length is 39 cm

Step-by-step explanation:

We will use the ratio method to solve the question

∵ A length, originally 9cm, is increased

∴ The original length = 9 cm

∵ The ratio of the new length to the old length is 13 : 3

→ That means the ratio is ⇒ New : Original is 13 : 3

∴ The ratio New : Original = 13 : 3

→ By using the ratio method

→  New  :  Original

→  13      :   3

→  x        :   9

→ By using cross multiplication

∵ x × 3 = 13 × 9

∴ 3x = 117

→ Divide both sides by 3

∵ =

∴ x = 39

∵ x represents the new length

∵ x = 39

∴ The new length is 39 cm