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June 30th, 2018, 10:15 PM   #1
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How is this big formula obtained?

A man bought 90 watches and marked a tag price 25% of the C.P He started to give 10% discount for the cash payment and 5% discount for others He sold 3/4 of the stock in cash payment. If he earned 2250 as a profit. Find the cost of each watch.

Solution: X(5/4)(9/10)(30) + X(5/4)(19/20)(10) = 2250

How is this big formula obtained?
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June 30th, 2018, 10:42 PM   #2
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Are you sure the man didn't buy 40 watches instead of 90?
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June 30th, 2018, 10:50 PM   #3
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Quote:
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Are you sure the man didn't buy 40 watches instead of 90?
he's also forgotten to subtract out the initial cost of the watches
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June 30th, 2018, 10:54 PM   #4
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he's also forgotten to subtract out the initial cost of the watches
Yes, my next question was going to be regarding whether revenue rather than profit was 2250.
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June 30th, 2018, 11:50 PM   #5
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Oh sorry it is 40 watches
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July 1st, 2018, 12:16 AM   #6
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Quote:
Originally Posted by Ganesh Ujwal View Post
. . . a tag price 25% of the C.P.
I assume you meant "a tag price 25% in excess of the C.P." or words to that effect, which would make the tag price 5/4 times the C.P. (cost price). The equation seems to be using "X" for the cost price.
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July 1st, 2018, 08:05 AM   #7
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Your problem reworded:
Quote:
Originally Posted by Ganesh Ujwal View Post
A man bought 40 watches and marked a tag price 25% of the C.P.
He gave 10% discount for cash payment and 5% discount for others.
He sold 3/4 of the stock in cash payment.
If his net profit was 2250, find the C.P. of each watch.

Solution: X(5/4)(9/10)(30) + X(5/4)(19/20)(10) = 2250
Ganesh, look at X(5/4)(9/10)(30):

5/4 = 1.25 (tag price = C.P. + 25%)
9/10 = .9 = 1 - .10 (cash payment price reduced by 10%)
30 = 3/4 * 40 (number sold as cash payment)

Do you understand that?
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July 1st, 2018, 08:17 PM   #8
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Quote:
Originally Posted by Denis View Post
Your problem reworded:

Ganesh, look at X(5/4)(9/10)(30):

5/4 = 1.25 (tag price = C.P. + 25%)
9/10 = .9 = 1 - .10 (cash payment price reduced by 10%)
30 = 3/4 * 40 (number sold as cash payment)

Do you understand that?
Why multiply all of them?
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July 1st, 2018, 09:56 PM   #9
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The multiplication by 5/4 to get the tag price is because that is equivalent to adding 25% to the CP. Similarly, the multiplication by 9/10 is because that is equivalent to giving a discount of 10% of the tag price. The multiplication by 30 is to give the total amount received for 30 watches that were sold at a 10% discount. These multiplications could be done in succession, but the result would be the same as the result of doing them all together.
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July 2nd, 2018, 10:10 AM   #10
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Quote:
Originally Posted by Ganesh Ujwal View Post
Solution: X(5/4)(9/10)(30) + X(5/4)(19/20)(10) = 2250
You also goofed up on the shown solution; should be:

X = cost price of 1 watch (ALWAYS declare your variables!)

X(5/4)(9/10)(30) + X(5/4)(19/20)(10) - 40X = 2250

Solve: X = 400

May we ask you to be more careful? Thank you.
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