JAMB Mathematics 1984 Question 5

Question 5

Quadratic Equations

If the price of oranges was raised by ½k per orange, the number of oranges a customer can buy for ₦2.40 will be less by 16. What is the present price of an orange?

A.2½k
B.3½k
C.5½k
D.20k
E.21½k.

Show the answer and explanation

Answer: A (2½k)

Explanation

With price x kobo: 240/x − 240/(x + ½) = 16. This simplifies to 2x² + x − 15 = 0, i.e. (2x − 5)(x + 3) = 0, so x = 2½k.