At a railway station, a tooth seller bought few datuns (wooden toothbrush) at the rate of 6 per Rs. 100. Second time he bought he same number of datuns at rate of 5 per Rs. 100. He mixed both the lots and then sold the datuns at the rate o7 per Rs. 200. In this business he had a loss of Rs. 1320.What are the number of datuns he bought ?
At a railway station, a tooth seller bought few datuns (wooden toothbrush) at the rate of 6 per Rs. 100. Second time he bought he same number of datuns at rate of 5 per Rs. 100. He mixed both the lots and then sold the datuns at the rate o7 per Rs. 200. In this business he had a loss of Rs. 1320.What are the number of datuns he bought ? Correct Answer 168
Given∶
He bought few datuns at the rate of 6 per Rs. 100.
Second time he bought he same number of datuns at rate of 5 per Rs. 100.
He mixed both the lots and then sold the datuns at the rate of 7 per Rs. 200.
He had a loss of Rs. 1320.
Formula Used∶
Basics of Profit & Loss and Unitary Method.
S.P. = C.P. - Loss
Calculation∶
Let the number of datuns he bought on each occasion be 'x'.
For the 1st transaction, he bought x datuns paying Rs. 100 for 6.
Applying unitary method to find the total cost of x number of datuns.
He bought first time x datuns for Rs. 100
So, his cost per datun = 100/6
and, for x numbers of datuns, total cost = 100x/6
Similarly for 2nd purchase,
Total cost for x number of datuns = 100x/5
For 2x number of datuns, his totalcost, C.P. = 100x/6 + 100x/5 = 1100x/30
He sold it athe rate of 7 for Rs. 200, that is at a sale price per datun = Rs. 200/7
For 2x number of datuns, S.P. = Rs. 400x/7
Also, S.P. = C.P. - Loss
⇒ 400x/7 = 1100x/30 - 1320
⇒ 330x = 1320 × 21
⇒ x = 84
⇒ 2x = 2 × 84 = 168
∴ Total number of datuns he bought was168.