Question

The Cost Price of 11 Pens is equal to the Selling Price of 10 Pens. Find the Gain or Loss Percent.

Answer 1

LET THE COST PRICE OF 1 PEN=X
THEN CP OF 11 PENS=11X=TOTAL COST 
AND CP OF 10 PENS=10X=TOTAL SALE
HERE, LOSS=11X-10X=X
LOSS%=(X)(100)/11X=9.09%

Answer 2

Gain or Loss Percentage is 10%

Step-by-step explanation:

Consider, that the C.P of 11 pens is taken as y

Then the C.P of 1 pen is $=\frac{y}{11}$

S.P of 10 pens is taken as = y

S.P of 1 pen $=\frac{y}{10}$

From the question, the C.P of the 11 pen is equal to the S.P of the 10 pens.  So, some percentage of gain is there.

$\frac{y}{10}>\frac{y}{11}$

$\text{Selling Price} > \text{Cost Price}$

The S.P of the 11 pens is greater than the C.P of the 11 pens. So, there is a gain.

$P=\frac{y}{10}-\frac{y}{11}$

$=\frac{11 y-10 y}{110}$

$=\frac{y}{110}$

$P \%=\frac{\frac{y}{110}}{\frac{y}{11}} \times 100$

$P \%=10 \%$