In an objective paper, there are two sections of 10 questions each.For "section 1", each question has 5 options and only one optionis correct and "section 2" has 4 options with multiple answers and marks for a question in this section is awarded only if he ticks all correct answers. Marks for each question in "sectionl 1" is 1 and in "section 2" is 3. (There is no negative marking.) If a candidate in total attempts 4 questions by guessing ,then the probability of scoring 10marks is

Options

A. `1//5(1//15)^(3)`
B. `4//5(1//15)^(3)`
C. `1//5(14//15)^(3)`
D. None of these

Answer

D

Explanation

Socroing 10 marks from questions can be done in `3+3+3+1=10` ways so as to answer 3 questions from section 2 and 1 question form section 1 correctly. Hence, the required probability is
`(""^(10)C_(3)""^(10)C_(1))/(""^(20)C_(4))=1/5((1)/(15))^(3)`