Question

Of the 25 questions in a unit, a student has worked out only 20. In a sessional test of that unit, two questions were asked by the teacher, The probability that the student can solve both the questions correctly, is

• A. $\frac{8}{25}$
• B. $\frac{17}{25}$
• C. $\frac{9}{10}$
• D. $\frac{19}{30}$

Answer 1

The correct option is D $\frac{19}{30}$

Total number of questions = 25
Student has worked out = 20
The probability that the student can solve both the questions correctly
$=\frac{{}^{20}{C}_2}{{}^{25}{C}_2}$
=$\frac{19}{30}$