Question

8 pens and 3 pencils cost as much as 3 pens and 9 pencils. What is the ratio of the cost of one pen to the cost of one pencil?
1. 5 : 4
2. 6 : 7
3. 6 : 5
4. 3 : 2

Answer 1

Correct Answer - Option 3 : 6 : 5

Given:

8 pens and 3 pencils cost is equal to 3 pens and 9 pencils.

Calculation:

let the cost of one pen be Rs. X

∴  the cost of 8 pens = 8X 

and, the cost of 3 pens = 3X

Again, let the cost of one pencil be Rs. Y

∴ the cost of 3 pencils = 3Y

and, the cost 9 pencils = 9Y

According to question: 

8X + 3Y = 3X + 9Y

⇒ 8X - 3X = 9Y - 3Y

⇒ 5X = 6Y

⇒ X/Y = 6/5

⇒ X : Y = 6 : 5

∴ the ratio of the cost of one pen to the cost of one pencil is 6 : 5.