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KarishmaB MartyMurray Any quick method to solve this one ? Kindly help.
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Bunuel Please check the OA and tell me where I am wrong.

Given: A utilities company sells electrical wiring at $7 per 15 meters, which costs them around $3 per 15 meters to make. If a customer purchases at least 300 meters, the company offers a 10% discount on the rate, with the discount given increasing by 5% for each additional 300 meters, such that 600 meters would receive a 15% discount on the total bill.

Asked: They must sell less than what length of wire if they wish to have at least a 40% profit margin?

For at least 40% profit margin, selling price > 3*1.4 = $4.2 per 15 meters
If Discount possible is D%, selling price = 7(1-D%/100) > 4.2
1 - D%/100 > 4.2/7 = .6
D% < 40%

10% + 5%(x-300)/300 < 40%
x - 300 < 6*300 ; x < 2100 meters
They must sell less than 300 + 6*300 = 2100 meters length of wire.

IMO E­
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sayan640 Bunuel

Please check my revised solution.
Bunuel is requrested to revise OA if needed.

sayan640
Please delete this comment since I have taken min 50% profit margin instead of 40%.
sayan640
E is incorrect.
Kinshook
Given: A utilities company sells electrical wiring at $7 per 15 meters, which costs them around $3 per 15 meters to make. If a customer purchases at least 300 meters, the company offers a 10% discount on the rate, with the discount given increasing by 5% for each additional 300 meters, such that 600 meters would receive a 15% discount on the total bill.

Asked: They must sell less than what length of wire if they wish to have at least a 40% profit margin?

For 50% profit margin, selling price = 3*1.5 = $4.5 per 15 meters
Discount possible = 7(1-D%/100) = 4.5
1 - D%/100 = 4.5/7 = 9/14
D%/100 = 1 - 9/14 = 5/14
D% = 100*5/14 = 500/14 = 35 10/14 %

For 35% discount, length required to be sold = 300 + 25/5 * 300 = 1800 meters

IMO E­
­
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I think your mistake is in the highlighted part. The answer is D indeed.
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Bunuel Please check the OA and tell me where I am wrong.

Given: A utilities company sells electrical wiring at $7 per 15 meters, which costs them around $3 per 15 meters to make. If a customer purchases at least 300 meters, the company offers a 10% discount on the rate, with the discount given increasing by 5% for each additional 300 meters, such that 600 meters would receive a 15% discount on the total bill.

Asked: They must sell less than what length of wire if they wish to have at least a 40% profit margin?

For at least 40% profit margin, selling price > 3*1.4 = $4.2 per 15 meters
If Discount possible is D%, selling price = 7(1-D%/100) > 4.2
1 - D%/100 > 4.2/7 = .6
D% < 40%


10% + 5%(x-300)/300 < 40%
x - 300 < 6*300 ; x < 2100 meters
They must sell less than 300 + 6*300 = 2100 meters length of wire.

IMO E­
­
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KarishmaB MartyMurray Any quick method to solve this one ? Kindly help.
­A utilities company sells electrical wiring at $7 per 15 meters, which costs them around $3 per 15 meters to make. If a customer purchases at least 300 meters, the company offers a 10% discount on the rate, with the discount given increasing by 5% for each additional 300 meters, such that 600 meters would receive a 15% discount on the total bill. They must sell less than what length of wire if they wish to have at least a 40% profit margin?

The current price is $7.

Profit Margin \(= \frac{Price - Cost}{Price}\)

So, the price after discounts, p, at which the profit margin will be at least 40% will be such that \(\frac{p - 3}{p} = 0.40\).

Solve for the mininum price p:

\(\frac{p - 3}{p} = 0.40\)

\(p - 3 = 0.40p\)

\(0.60p = 3\)

\(p = 5\)

So, the minimum price at which they can make a 40% margin is $5.

$7 - $5 = $2

So, we can discount the price a max of $2.

$2/$7 ≈ 29%

So, we can discount the price a max of 29%.

10% + (3 * 5%) = 25%

10% + (4 * 5%) = 30%

So, the price must be discounted a max of 4 times, meaning under 5 times.

300 * 5 = 1500

(A) 600 meters

(B) 900 meters

(C) 1200 meters

(D) 1500 meters

(E) 1800 meters­


Correct answer:
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Bunuel
­A utilities company sells electrical wiring at $7 per 15 meters, which costs them around $3 per 15 meters to make. If a customer purchases at least 300 meters, the company offers a 10% discount on the rate, with the discount given increasing by 5% for each additional 300 meters, such that 600 meters would receive a 15% discount on the total bill. They must sell less than what length of wire if they wish to have at least a 40% profit margin?

(A) 600 meters
(B) 900 meters
(C) 1200 meters
(D) 1500 meters
(E) 1800 meters
­CP = $3
Marked Price = $7
Profit Margin (calculated on SP) required is at least = 40%

CP + Profit = SP
$3 + 40% of S = S
which gives S = $5

Hence the selling price can fall to at most $5 which means that the maximum discount that can be given = \(\frac{2}{7} = 29%\) (Recall 1/7 = 14.28%)

This means that we cannot give a 30% discount. The discount should not reach (10% + 4*5%).
So the length of the wire should not reach (300 + 4*300) = 1500 meters

Answer (D)
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Marked price per 15 m = $7, cost per 15 m = $3.

Profit margin = (selling price − cost) / selling price. For a discount d selling price per 15 m is
7(1−d).

Require

[{7(1-d)}− 3 ] / {7(1−d)} ≥ 0.40

1 −[ 3/ {7(1−d)}] ≥ 0.4

1-0.4 ≥ [3/ {7(1−d)}]

0.6 ≥ [3/ {7(1−d)}]

7(1−d) ≥ 3/0.6

7(1−d) ≥ 5

1−d ≥ 5/7

2/7 ≈ 28.57%.

300 m → 10%, 600 m → 15%, 900 m → 20%, 1200 m → 25%, 1500 m → 30%.

Hence , <1500m, so Option D.
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