Apaec Posted February 12, 2016 Share Posted February 12, 2016 (edited) maths/logic puzzle! I borrowed 100 roubles from you. Then I went shopping and lost that money. But then I met my friend and borrowed 50 roubles from her. I was able to buy two chocolate bars costing 10 roubles each, leaving me 30 roubles. I repaid part of my debt to you with that 30 roubles, making me owe you further 70 roubles, as well as 50 roubles to my friend. In all, 120 roubles. Plus I have two chocolate bars. Total: 140 roubles. I am 10 roubles short! Where are they? PS rouble is russian currency, for those who didn't know. Edit: have the answer: Think about it. The 50 roubles borrowed from the friend doesn't get lost anywhere. Imagine you didn't buy any chocolate bars, you just gave back 30/50 roubles. That leaves you with 20 roubles, with your total debt being 120 roubles. You own 20 roubles, and you owe 120, so if you wanted to you could repay more of your debt with the remaining 20 roubles and get your debt down to 100 roubles. This 100 roubles is the money which you initially borrowed (and proceeded to lose). Edited February 12, 2016 by Apaec Quote Link to comment Share on other sites More sharing options...
Botre Posted February 12, 2016 Share Posted February 12, 2016 (edited) brb changing my answer Edited February 12, 2016 by Botre 1 Quote Link to comment Share on other sites More sharing options...
September Posted February 12, 2016 Share Posted February 12, 2016 You removed 10 roubles by replacing the 30 roubles you paid with chocolate bars worth 20. Quote Link to comment Share on other sites More sharing options...
Shudsy Posted February 12, 2016 Share Posted February 12, 2016 (edited) By repaying the 100, the question just becomes more confusing. Lets try to explain this. Debt: 100 50 You spend 20, and you got 30 + 2 chocolates left. You repay 30. Debt: 100 20 You're now 120 in debt + the chocolate you got yourself. Which adds up. Sell the chocolate for 20, and repay 20. You're now 100 in debt. You're mixing what you have and what you owe. TL:DR: Don't do 120 + 20 = 140. Do 120 - 20 = 100. Calculate how much you owe. Edited February 12, 2016 by Shudsy Quote Link to comment Share on other sites More sharing options...
Okabe Posted February 12, 2016 Share Posted February 12, 2016 Because you are adding what you have to what you owe. +100 +50 -30 you owe 120 (so -120) Quote Link to comment Share on other sites More sharing options...
Apaec Posted February 12, 2016 Author Share Posted February 12, 2016 By repaying the 100, the question just becomes more confusing. Lets try to explain this. Debt: 100 50 You spend 20, and you got 30 + 2 chocolates left. You repay 30. Debt: 100 20 You're now 120 in debt + the chocolate you got yourself. Which adds up. Sell the chocolate for 20, and repay 20. You're now 100 in debt. You're mixing what you have and what you owe. TL:DR: Don't do 120 + 20 = 140. Do 120 - 20 = 100. Calculate how much you owe. you nailed it ! well done Quote Link to comment Share on other sites More sharing options...
Botre Posted February 12, 2016 Share Posted February 12, 2016 (edited) The formula to calculate the total (amount of involved money, ambigious) is: All the money you owe to person 1 + all the money you owe to person 2 = 150 + 100 = 150 However, the question assumes that the formula to calculate the total amount of involved money is: Part of the money you owe to person 1 + all of the money you owe to person 2 + chocolates = 70 + 20 + 20 = 140 The formula presented by the question is bogus. Edited February 12, 2016 by Botre Quote Link to comment Share on other sites More sharing options...
jakeybob Posted February 12, 2016 Share Posted February 12, 2016 boooring its friday im drunk Quote Link to comment Share on other sites More sharing options...
Shudsy Posted February 13, 2016 Share Posted February 13, 2016 boooring its friday im drunk Why would you drink while sitting at the computer. Quote Link to comment Share on other sites More sharing options...
ANIMA VESTRA Posted February 13, 2016 Share Posted February 13, 2016 Why would you drink while sitting at the computer. crippling alcoholism Quote Link to comment Share on other sites More sharing options...
