A test has 50 questions. A student scores 1 mark for a correct answer, –1/3 for a wrong
answer, and –1/6 for not attempting a question. If the net score of a student is 32, the number
of questions answered wrongly by that student cannot be less than
1. 6 2. 12 3. 3 4. 9
Soln. (3) — Let the number of correct answers be ‘x’, number of wrong answers be ‘y’ and
number of questions not attempted be ‘z’.
Thus, x + y + z = 50 … (i)
And x – y – z 32
3 6
The second equation can be written as,
6x – 2y – z = 192 … (ii)
Adding the two equations we get,
7x – y = 242 or x = 242 + y
7
Since, x and y are both integers, y cannot be 1 or 2. The minimum value that y can
have is 3.
can u explain why Y can not be 1 or 2....i tried to make 242/7+Y integer but even 3 is not enough
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