The price of an item is 10% cheaper in an online store S compared to the price at another online store M. Store S charges Rs. 150 for delivery. There are no delivery charges for orders from the store M. A person bought the item from the store S and saved Rs. 100.
What is the price of the item at the online store S (in Rs.) if there are no other charges than what is described above?
2500
2250
1750
1500
ANSWER
The price of the item at store S is Rs. 2250, option (B).
Official answer: BSource: Official answer key, GATE 2022 EE (IIT Kharagpur)
Let the item's price at store M be . The item is 10% cheaper at S than at M, so the 10% is taken on M's price, and the price at S is .
Total paid at S = item price + delivery = . Total paid at M = , because M charges no delivery.
The saving is what the person would have paid at M minus what they paid at S: .
Set the saving equal to Rs. 100:
So the price at S is .
Check: buying from S costs , against at M, a saving of , as the question says. The answer is (B).
KEY IDEA
"10% cheaper at S than at M" means the 10% is taken on M's price, so S's price is . The saving is M's price minus everything paid at S, delivery included: .
WATCH OUT FOR
Taking the 10% on the wrong price. If you write M's price as , you get and , which is option (A). That is actually M's price, not S's. Two other slips: forgetting the Rs. 150 delivery charge ( gives Rs. 900 at S, which is not an option), and answering with M's price of 2500 when the question asks for S's.
From the GATE 2022 EE paper. Every question of this paper · Download the full paper · All 58 Numerical questions, with notes
