Indian Institute of Foreign Trade 2015 Solved Paper

(b) Rahul has scored 240 marks in first three quizzes.i.e. Average marks for three quizzes =

70+90+80

3

= 80
So, to get an average internal marks more than 80, he has to score more than 80 marks in the last quiz. This is Possible if,
I. He attempts 9 questions correctly Now, Number of ways to attempt 9 questions correctly out of 10questions = 10C9= 10 ways
II. He attempts all 10 questions correctly number of orginally ways = 2Total Number of ways = 210 = 1024
∴Required probability =

10+1

1024

=

11

1024