Discussion

Explanation:

Let the total number of questions be x.

Let Sunita attempt ‘a’ number of questions correct.

Then, $\frac{a}{x}$ = $\frac{75}{100}$ = $\frac{3}{4}$

⇒ 4a = 3x   ...(1)

Also, according to the given condition, 

$\frac{a+4}{x}$ = $\frac{85}{100}$ = $\frac{17}{20}$

[∵ Out of 6 additional questions attempted, she got 2 wrong i.e., she got 4 more correct answers]

⇒ 20a + 80 = 17x   ...(2)

From (1) and (2),

⇒ 15x + 80 = 17x

⇒ x = 40

∴ There are a total 40 questions in the exam.

Alternately,
Because of 4 additional correct answers her marks increased by 10%.

⇒ 10% of total no. of questions = 4

⇒ total no. of questions = 4/10% = 40

Hence, option (c).

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