A CD player and a DVD player have the same price. If the price of the CD player goes up by 10% and that of the DVD player is decreased by 5%, how much more will it cost to buy 5 CD players and 5 DVD players?

Explanation: মনে করি, আগে প্রত্যেকটি CD player and DVD player এর price ছিলো \(= Tk. 10\). অতএব, 5টি CD Player ও 5টি DVD Player এর দাম ছিলো \(= 5\times10 + 5\times10 = Tk. 100\). এখন CD Player এর দাম বেড়ে হয় \(= 10\times1.10 = Tk. 11\) এবং DVD Player এর দাম কমে হয় \(= 10\times0.95 = Tk. 9.5\). অতএব, 5টি CD Player ও 5টি DVD Player এর মোট দাম হয় \(= 5\times11 + 5\times9.5 = 55 + 47.5 = Tk. 102.5\). Increase in price \(= 102.5 - 100 = Tk. 2.5\). Percentage increase \(= \frac{2.5}{100}\times100 = 2.5\%\). None of these is the correct choice, but given the options and the calculated value, the correct option is [None of these].