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In a quiz competition, a student answers n questions corr...

In a quiz competition, a student answers n questions correctly and was given D(n + 50) for each question correctly answered. If he gets D600.00 altogether, how many questions did he answer correctly?

A.

18

B.

15

C.

12

D.

10

Correct answer is D

let the number of question = n

n(n + 50) = 600

n2 + 50n - 600 - 0 by quadratic formular

x = b±b24ac2

n = 50±5024(1)(600)2(1)

= 50±49002

= 50+702

= 202

= 10