Institution: Bangladesh Bank Exam: Officer (General) -Ansar VDP Unnayan | BD House Building Finance Corporation 28.09.2018 ||
Topic: Mathematics (সাধারণ গণিত), Subject: Mathematics (সাধারণ গণিত)

Best Answer Explained in Below-:

To determine the average price of a pen, we start by analyzing the information given in the problem. We know that 30 pens and 75 pencils were purchased for a total of Tk. 510. We are also informed that the average price of a pencil is Tk. 2.

First, we calculate the total cost of the pencils. Since there are 75 pencils and each costs Tk. 2, the total cost for the pencils is:

Total cost of pencils = Number of pencils × Average price of a pencil
Total cost of pencils = 75 × 2 = Tk. 150.

Now, we know the total expenditure for both pens and pencils is Tk. 510. To find the total cost for the pens, we subtract the total cost of the pencils from the overall expenditure:

Total cost of pens = Total expenditure - Total cost of pencils
Total cost of pens = 510 - 150 = Tk. 360.

Now that we have the total cost for the 30 pens, we can find the average price per pen by dividing the total cost of the pens by the number of pens:

Average price of a pen = Total cost of pens / Number of pens
Average price of a pen = 360 / 30 = Tk. 12.

Thus, the average price of a pen is Tk. 12, which corresponds to option D.