Question

A person ordered 5 pairs of black socks and some pairs of brown socks. The price of a black pair was thrice that of a brown pair. While preparing the bill, the bill clerk interchanged the number of black and brown pairs by mistake which increased the bill by 100%. What was the number of pairs of brown socks in the original order? 

(a) 10 (b) 15 (c) 20 (d) 25

Answer 1

(d) Let number of a pairs of brown socks = y 

Price of brown socks = x 

Price of black socks = 3x 

According to question 

⇒ 5 * 3x + yx = 100    ... (i) 

Now, clerk has interchanged socks pairs then price is increased by 100%

∴ So, number of brown socks = 25