A) 20
B) 22
C) 24
D) 26
Correct Answer: C
Solution :
Let the number of questions whose answer is known to the student be x and questions attempted by guessing be y. |
Then, x+y=120 ...(i) |
and … (ii) |
On adding Eqs. (i) and (ii), we get |
5x = 480 |
\[\Rightarrow \,\,\,x=\frac{480}{5}=96\] |
Put x = 96 in Eq. (i), we get |
\[96+y=120\Rightarrow y=120-96=24\] |
He guesses only 24 questions. |
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