Question

In what ratio must a grocer mix two varieties of pulses costing Rs.15 and Rs.20 per kg
respectively so as to get a mixture worth Rs.16.50 kg?
a) 3 : 7
b) 5 : 7
c) 7 : 3
d) 7 : 5
e) None of these

Answer 1

Let the amount of pulse of price ₹15 = x
and the amount of pulse of price ₹20 = y

Then total amount of mixture = x+y kg

total cost of mixture = 15x + 20y

but the price per kg of the mixture= ₹16.50

so, total price of x+y kg = 16.50(x+y)

According to question;

16.50(x+y) = 15x + 20 y

or, 16.50x + 16.50y = 15x + 20y

or, 1.50x = 3.50y

or, x/y = 3.50/1.50 = 0.7/0.3 = 7/3

so, required ratio is 7 : 3.

Answer 2

Hey there!

Good question :D

The cost of 1st vareity : Rs.15
The cost of 2nd vareity : Rs. 20

Mean price = 16.5 kg

According to law of alligation,

$\frac{20 - 16.5}{16.5 - 15}$

$\frac{3.50}{1.50}$

$\frac{35}{15}$

$\frac{7}{3}$

7:3

Required ratio is 7:3