In a coffee estate there are two varieties of coffee. At what ratio must the two varieties of coffee be mixed together into one at ₹40 per kg and the other at ₹50 per kg? The cost of the mixture is ₹43 per kg.
Let the ratio in which the two varieties are mixed be a:b
Hence, $$\ \frac{40a+50b}{a+b}$$ = 43
$$\ 40a+50b=43a+43b$$
This gives us 7b = 3a or a:b = 7:3
The option has an error; this happened in the actual exam paper, so we can't change it.