how many kilos of tea worth Rs. 72 per kg should be mixed with 10 kg of tea worth Rs. 90 per kg to produce a mixture , which will together cost Rs. 78 per kg ?
Given, 10kg of tea worth Rs 90 per kg is taken.
Let x kg of tea worth Rs 72 per kg is mixed with 10kg of tea worth Rs 90 per kg.
and total cost of Rs. 72 per kg quality tea = Rs x × 72 = Rs 72x
After mixing total amount of Rs. 78 per kg quality tea obtained = (x + 10) kg
So, cost of tea obtained after mixing = Rs (x + 10) × 78 = Rs 78x + 780
Now, cost before mixing = cost after mixing
⇒ 72x + 900 = 78x + 780
⇒ x = 20
Hence, 20 kg of tea worth Rs. 72 per kg should be mixed with 10 kg of tea worth Rs. 90 per kg to produce a mixture together costing Rs. 78 per kg.