Q. 3 B4.3( 7 Votes )

Represent the following situations mathematically:

A shopkeeper buys a number of books for Rs. 80. If he had bought four more books for the same amount, the book would have cost Re. 1 less.

Answer :

Let ‘x’ be the number of books bought by the shopkeeper.

Cost of one book = Rs. 80 ÷ x.

[ the total cost of books is Rs. 80]

Cost of one book when he buys 4 more books for same rate = Rs. 80 ÷ (x + 4).

When he buys four more books for the same amount; it will cost Re. 1 per book less than the previous.

80 ÷ (x + 4) = (80 ÷ x) − 1

80x = (x + 4) (80 − x)

80x = 80x − x2 + 320 − 4x

x2 + 4x + 320 = 0

Rate this question :

How useful is this solution?
We strive to provide quality solutions. Please rate us to serve you better.
Related Videos
Get To Know About Quadratic Formula42 mins
Quiz | Knowing the Nature of Roots44 mins
Take a Dip Into Quadratic graphs32 mins
Foundation | Practice Important Questions for Foundation54 mins
Nature of Roots of Quadratic EquationsFREE Class
Getting Familiar with Nature of Roots of Quadratic Equations51 mins
Quadratic Equation: Previous Year NTSE Questions32 mins
Champ Quiz | Quadratic Equation33 mins
Balance the Chemical Equations49 mins
Know More About The Quadratic Formula43 mins
Try our Mini CourseMaster Important Topics in 7 DaysLearn from IITians, NITians, Doctors & Academic Experts
Dedicated counsellor for each student
24X7 Doubt Resolution
Daily Report Card
Detailed Performance Evaluation
view all courses