WAEC Mathematics 2020 Objective — Question 22

Question 22 of 50 from the West African Examinations Council (WAEC) Mathematics 2020 Objective paper, with the correct answer and a full explanation.

A man is five times as old as his son. In four years time, the product of their ages would be 340. If the son's age is y, express the product of their ages in terms of y.

A. 5y^2 - 16y - 380 = 0
B. 5y^2 + 24y - 308 = 0
C. 5y^2 - 16y - 330 = 0
D. 5y^2 + 24y - 324 = 0Correct

Explanation

Son's age=y, man's age=5y. In 4 years: son=y+4, man=5y+4. Product: (y+4)(5y+4)=340 => 5y^2+4y+20y+16=340 => 5y^2+24y+16-340=0 => 5y^2+24y-324=0.

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