Question

An article was sold for Rs. 144. If the percentage of profit was numerically equal to the cost price, the cost of the article was ____.

• A. Rs. 72
• B. Rs. 80
• C. Rs. 90
• D. Rs. 100

Answer 1

Answer: (B)

Rs. 80

Given in the question.

Selling price(S.P)$=144$

Profit$\%$=Cost price(C.P)

Cost price(C.P)$=?$

We know that,

$P\%=\frac{S.P-C.P}{C.P}\times 100$

$C.P=\frac{144-C.P}{C.P}\times 100$

$C.P^2=14400-100C.P$

$C.P^2+100C.P-14400=0$

$C.P^2+180C.P-80C.P-14400=0$

$C.P(C.P.+180)-80(C.P+180)=0$

$(C.P+180)(C.P-80)=0$

$C.P$ cannot be negative.

So,

$C.P=80$

Hence,the cost price of article is Rs $80$.