Simple equations STD VI

Lakshmi is a cashier in a bank. She has currency notes of denominations Rs 100, Rs 50 and Rs 10, respectively. The ratio of the number of these notes is 2:3:5. The total cash with Lakshmi is Rs 4,00,000. How many notes of each denomination does she have?

Answer:

Let total number of notes be y

So, fraction of notes of Rs 100 denomination = 2/ (2+3+5) = 2/ 10 = 0.2

So, fraction of notes of Rs 50 denomination = 3/ (2+3+5) = 3/ 10 = 0.3

So, fraction of notes of Rs 100 denomination = 5/ (2+3+5) = 5/ 10 = 0.5

Therefore, 0.2y x 100 + 0.3y x 50 + 0.5y x 10 = 400000

Or 20y +15y + 5y = 400000

Or, 40y = 400000

Or, y = 400000/40 = 10000

So, 100 denomination notes = 0.2 x 10000 = 2000

So, 50 denomination notes = 0.3 x 10000 = 3000

So, 10 denomination notes = 0.5 x 10000 = 5000

Check:

2000 x 100 = 200000

3000 x 50 = 150000

5000 x 10 = 50000

SO, total = 200000 + 150000 + 50000 = 400000