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Question

A dealer sold 6 sewing machines for Rs. 63,000 with a profit of 5%. For how much should be sell 8 machines if he intends to earn 15% profit?

This question was previously asked in
SSC CGL 2019 (Tier 2) GS Finance & Economics Previous Year Paper (17-Nov-2020)
The correct answer is

Rs. 92,000

Understanding the Problem: Sewing Machine Profit Calculation

The question asks us to determine the selling price needed for 8 sewing machines to achieve a 15% profit, given the selling price and profit percentage for 6 machines.

To solve this, we first need to find the original cost price (CP) of the machines. The cost price is the base value upon which profit or loss is calculated. Once we know the cost price per machine, we can calculate the total cost price for 8 machines and then determine the selling price required for a 15% profit.

Step-by-Step Solution for Dealer Profit

Step 1: Calculate the Cost Price of 6 Sewing Machines

We know the selling price (SP) of 6 sewing machines is Rs. 63,000 and the profit earned is 5%.

The relationship between SP, CP, and Profit Percentage is:

\( SP = CP \times (1 + \frac{Profit\%}{100}) \)

Plugging in the given values:

\( 63000 = CP_{6 \text{ machines}} \times (1 + \frac{5}{100}) \)

\( 63000 = CP_{6 \text{ machines}} \times (1 + 0.05) \)

\( 63000 = CP_{6 \text{ machines}} \times 1.05 \)

Now, we can find the CP of 6 machines:

\( CP_{6 \text{ machines}} = \frac{63000}{1.05} \)

\( CP_{6 \text{ machines}} = \frac{63000 \times 100}{105} \)

\( CP_{6 \text{ machines}} = \frac{6300000}{105} \)

Performing the division:

\( CP_{6 \text{ machines}} = 60000 \)

So, the cost price of 6 sewing machines is Rs. 60,000.

Step 2: Calculate the Cost Price of 1 Sewing Machine

If 6 machines cost Rs. 60,000, the cost price of one machine is:

\( CP_{1 \text{ machine}} = \frac{CP_{6 \text{ machines}}}{6} \)

\( CP_{1 \text{ machine}} = \frac{60000}{6} \)

\( CP_{1 \text{ machine}} = 10000 \)

The cost price of one sewing machine is Rs. 10,000.

Step 3: Calculate the Cost Price of 8 Sewing Machines

To find the cost price of 8 machines, we multiply the cost price of one machine by 8:

\( CP_{8 \text{ machines}} = CP_{1 \text{ machine}} \times 8 \)

\( CP_{8 \text{ machines}} = 10000 \times 8 \)

\( CP_{8 \text{ machines}} = 80000 \)

The cost price of 8 sewing machines is Rs. 80,000.

Step 4: Calculate the Selling Price of 8 Sewing Machines for 15% Profit

Now we want to find the selling price (SP) for these 8 machines to earn a 15% profit on their cost price (Rs. 80,000).

Using the formula \( SP = CP \times (1 + \frac{Profit\%}{100}) \):

\( SP_{8 \text{ machines}} = CP_{8 \text{ machines}} \times (1 + \frac{15}{100}) \)

\( SP_{8 \text{ machines}} = 80000 \times (1 + 0.15) \)

\( SP_{8 \text{ machines}} = 80000 \times 1.15 \)

Performing the multiplication:

\( SP_{8 \text{ machines}} = 80000 \times 1.15 \)

\( SP_{8 \text{ machines}} = 92000 \)

The dealer should sell 8 sewing machines for Rs. 92,000 to earn a 15% profit.

Summary of Calculations

ItemValue
SP of 6 machinesRs. 63,000
Profit % on 6 machines5%
CP of 6 machinesRs. 60,000
CP of 1 machineRs. 10,000
CP of 8 machinesRs. 80,000
Desired Profit % on 8 machines15%
Required SP for 8 machinesRs. 92,000

Conclusion

To earn a 15% profit, the dealer should sell 8 sewing machines for Rs. 92,000.

Revision Table: Key Concepts in Profit & Loss

TermDefinitionFormula Example
Cost Price (CP)The original price at which an item is bought.-
Selling Price (SP)The price at which an item is sold.-
ProfitWhen SP > CP. Calculated as SP - CP.\( \text{Profit} = \text{SP} - \text{CP} \)
LossWhen SP < CP. Calculated as CP - SP.\( \text{Loss} = \text{CP} - \text{SP} \)
Profit %Profit expressed as a percentage of the CP.\( \text{Profit}\% = (\frac{\text{Profit}}{\text{CP}}) \times 100 \)
Loss %Loss expressed as a percentage of the CP.\( \text{Loss}\% = (\frac{\text{Loss}}{\text{CP}}) \times 100 \)
SP with ProfitCalculating SP when CP and Profit% are known.\( \text{SP} = \text{CP} \times (1 + \frac{\text{Profit}\%}{100}) \)
SP with LossCalculating SP when CP and Loss% are known.\( \text{SP} = \text{CP} \times (1 - \frac{\text{Loss}\%}{100}) \)
CP from SP & Profit %Calculating CP when SP and Profit% are known.\( \text{CP} = \frac{\text{SP}}{1 + \frac{\text{Profit}\%}{100}} \)

Additional Information: Understanding Unitary Method in Pricing

This problem effectively uses the unitary method concept. By first finding the cost price of a single unit (one sewing machine), we can then easily scale that cost price to any number of units (8 machines in this case).

This approach is useful in many percentage-based problems involving multiple items. It breaks down a complex problem into simpler, per-unit calculations before scaling back up to the desired total quantity.

  • Calculate the base value (CP) for the initially given quantity.
  • Find the base value (CP) for a single unit.
  • Calculate the base value (CP) for the new quantity.
  • Apply the new percentage (profit or loss) to the new base value to find the target selling price.
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Similar Questions

  1. Radha bought a fridge and a washing machine together for Rs. 57300. She sold the fridge at a profit of 15% and washing machine at a loss of 24% and both are sold at the same price. The cost price of washing machine (in Rs.) is:

  2. A trader sells an article at 16% below its cost price. Had he sold it for Rs. 192.20 more, he would have gained 15%. The cost price (in Rs.) of the article is:

  3. A shopkeeper by selling 5 items, earns a profit equal to the selling price of 1 item. What is his profit percentage?

  4. An item is sold at two successive gains of 30% and 20%. If the final selling price is Rs. 31200, then what is the cost price (in Rs.)?

  5. By what fraction selling price (S. P.) must be multiplied to get the cost price (C. P.) if the loss is 20%?

  6. Remi earns a profit of 20% on selling an article at a certain price If she sells the articles for Rs. 8 more, she will gain 30% What is the original cost price of 16 such articles?

  7. On selling an article for Rs 123.40, the gain is 20% more than the amount of loss incurred on selling it for Rs.108. If the article is sold for Rs. 120.75, then what is the gain/loss per cent?

  8. An article is listed at Rs. 7,600 and the discount offered for the unit is 10%. What additional discount must be given to bring the net selling price to Rs. 5,814?

  9. A man sells two articles at Rs. 9,975 each. He gains 5% on one article and loses 5% on the other. Find his overall gain or loss.

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Important Questions from Successive Selling

  1. The increase in the price of a certain item was 25%. Then the price was decreased by 20% and then again increased by 10%. What is the resultant increase in the price?

  2. The selling price of 24 articles is equal to the cost price of 26 articles. If, due to a change in market conditions, the selling price of each article decreases by $10\%$ and the cost price of each article increases by $5\%$, what will be the new gain or loss percentage (correct to two decimal places)?
  3. Anil bought some articles at 6 for Rs. 8 and sold them at 10 for Rs. 12. His percentage loss or gain is:

  4. The price of an article becomes Rs. 63 after a decrease of 30 percent. Find the original price. (in Rs.)

  5. A man buys an article for 10 percent less than its value and sells it for 10 percent more than its value. His profit or loss percent is:

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