A tea seller bought 15 kg of Darjeeling tea at ₹300 per kg and 25 kg of Assam tea at ₹240 per kg. He mixed them together. Due to a slight drop in market prices, he had to sell the entire mixture at ₹260 per kg. Calculate his total profit or loss.
- (a)Loss of ₹100
- (b)Profit of ₹100
- (c)Profit of ₹200
- (d)Profit of ₹200
Answer
Why
Correct — A. Compare the total cost with the total sale.
Darjeeling: 15 × 300 = ₹4,500
Assam: 25 × 240 = ₹6,000
Total cost = ₹10,500 for 40 kg
Sale: 40 × 260 = ₹10,400
10,400 − 10,500 = −₹100, a loss of ₹100 → option (a)
Why the others are wrong
- (b)Profit of ₹100 — Right amount, wrong direction. The mixture costs 10,500 ÷ 40 = ₹262.50 a kg and sells at ₹260, so every kilogram loses money.
- (c)Profit of ₹200 — No profit is possible: the mixture sells at ₹260 a kg against an average cost of ₹262.50. The deal loses ₹2.50 on each of the 40 kg.
- (d)Profit of ₹200 — Printed with the same text as option (c), and wrong for the same reason: ₹260 a kg is below the ₹262.50 average cost, so the deal is a loss.
Concept
When two lots are mixed, the mixture's cost is the total cost divided by the total weight, not the plain average of the two rates.
The plain average, (300 + 240) ÷ 2 = ₹270, overstates the cost because more of the cheaper Assam tea went in. The weighted cost is 10,500 ÷ 40 = ₹262.50 a kg.
Profit or loss is then selling price minus cost: (260 − 262.50) × 40 = −₹100.
On the response sheet, options (c) and (d) are both printed as Profit of ₹200. Neither is correct, so the duplicate does not change the answer.
Key facts
- Mixture cost per kg = (q₁ × c₁ + q₂ × c₂) ÷ (q₁ + q₂).
- (15 × 300 + 25 × 240) ÷ 40 = ₹262.50 a kg.
- A selling price below the cost per kg means a loss on every kilogram sold.
Study next
Common traps
- Averaging ₹300 and ₹240 to ₹270: that ignores the 15 kg against 25 kg split and inflates the loss to ₹400.
- Getting the size right and the sign wrong: ₹100 is offered as both a loss and a profit.
15 Sep 2025, 16:00, Quant Q.15 runs this backwards: tea at ₹150 mixed 4 : 5 with a second quality sells at ₹130 with no profit or loss, so 4 × 150 + 5x = 9 × 130 and x = ₹114.
15 Sep 2025, 16:00, Quant Q.11 weights three notebook costs 3 : 4 : 3 the same way before comparing with the sale price, keyed a profit of 9.2%.
Related PYQs
No directly related past PYQ was found.