Let's solve each question step by step.

1. Profit Percentage on Tea Packet

• Cost Price (C.P.) = Rs. 20
• Profit = Rs. 4

Profit percentage formula: $\text{Profit Percentage} = \left( \frac{\text{Profit}}{\text{C.P.}} \right) \times 100$ Substitute the values: $\text{Profit Percentage} = \left( \frac{4}{20} \right) \times 100 = 20\%$

So, the profit percentage is 20%.

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2. Loss Percentage on Mangoes

• Cost Price (C.P.) = Rs. 300
• Selling Price (S.P.) = Rs. 255

Loss percentage formula: $\text{Loss Percentage} = \left( \frac{\text{C.P.} - \text{S.P.}}{\text{C.P.}} \right) \times 100$ Substitute the values: $\text{Loss Percentage} = \left( \frac{300 - 255}{300} \right) \times 100 = \frac{45}{300} \times 100 = 15\%$

So, the loss percentage is 15%.

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3. Profit or Loss on Pencils

• Cost Price per dozen = Rs. 10
• Number of dozens = 150
• Overhead expenses = Rs. 100
• Selling Price per pencil = Rs. 1.20

First, calculate the total cost: $\text{Total C.P.} = 150 \times 10 + 100 = 1500 + 100 = Rs. 1600$

Next, calculate the total selling price: $\text{Total S.P.} = 150 \times 12 \times 1.20 = 1800 \times 1.20 = Rs. 2160$

Now, calculate the profit: $\text{Profit} = \text{S.P.} - \text{C.P.} = 2160 - 1600 = Rs. 560$

Finally, calculate the profit percentage: $\text{Profit Percentage} = \left( \frac{560}{1600} \right) \times 100 = 35\%$

So, Karim made a 35% profit.

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4. Gain or Loss on Eggs

• Buying Rate: 10 eggs for Rs. 8 → Cost per egg = $\frac{8}{10} = 0.80$ Rs.
• Selling Rate: 8 eggs for Rs. 10 → Selling price per egg = $\frac{10}{8} = 1.25$ Rs.

Now, calculate the gain per egg: $\text{Gain per egg} = 1.25 - 0.80 = Rs. 0.45$

Now, calculate the gain percentage: $\text{Gain Percentage} = \left( \frac{0.45}{0.80} \right) \times 100 = 56.25\%$

So, the grocer made a 56.25% gain.

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Do you need further details on any of the calculations or concepts?

Here are 5 related questions to practice:

1. If a product is sold at a loss of 20%, and the selling price is Rs. 160, what was the cost price?
2. A merchant buys goods for Rs. 500 and sells them for Rs. 600. Find the profit percentage.
3. A seller buys 50 kg of sugar at Rs. 20 per kg and incurs Rs. 200 as transport cost. He sells the sugar at Rs. 25 per kg. What is his profit percentage?
4. If a bicycle is bought for Rs. 1500 and sold for Rs. 1350, what is the loss percentage?
5. A shopkeeper bought a TV for Rs. 5000 and sold it at a profit of 12%. What was the selling price?

Tip: To quickly find profit or loss percentages, always start with identifying the cost price and selling price.