Solution:
Given:
Brand A costing Rs. 15 per 100 g
Brand B costing Rs. 18 per 100 g
Sold the mixture at Rs. 20 per 100 g, making a profit of 20%
Formula used:
Profit% or Loss% = (Profit or Loss/Cost price) × 100
Calculation:
Let x gram of brand A and y gram of brand B is mixed.
For 100g brand A costs Rs. 15
For x g brand A will cost 10015x
For 100g brand B costs Rs. 18
For y g brand B will cost 10018x
So, the total cost price for (x + y) grams is
⇒ x+y=10015x+10018y ----(i)
Sold at Rs. 20 with 120% profit, Cost price will be
⇒ 100% = (12020)×100=Rs.6100
Cost price for 100g is Rs.6100,
Now find cost price for (x + y) grams
⇒x+y=(6100)×100(x+y)
⇒ x+y=6(x+y)
Put value of equation(i)
⇒ 10015x+10018y=6(x+y)
⇒ 90x + 108y = 100x + 100y
⇒ 8y = 10x
⇒yx=108=54
∴ The ratio of the mixture of Brand A and B is 4 : 5
Alternate Method:
∴ The ratio of the mixture of Brand A and B is 4 : 5