A man purchased equal number of bananas at two different rates-one at the rate of 8 taka per dozen and the other at the rate of 10 taka per dozen. After that, he sold those bananas at an average rate of 11 taka per dozen and thus made a profit of 100 taka. How many dozens of banana did he purchase altogether?
Explanation: ধরি, 8 taka per dozen এ কেনা হয় \(x\) টা কলা এবং 10 taka per dozen এ কেনা হয় \(x\) টা কলা। Total cost \(= 8x+10x = 18x\). Total no of dozens \(= 2x\). Total selling price \(= 11\times2x = 22x\). Profit \(= 22x-18x = 4x\). এখন, \(4x = 100 \Rightarrow 2x = 50\). The total number of dozens purchased is \(2x = 50\).
