Indian Institute of Foreign Trade 2015 Solved Paper

Question : 1 of 124

Marks: +1, -0

The internal evaluation for Economics course in an Engineering programme is based on the score of four quizzes. Rahul has secured 70, 90 and 80 in the first three quizzes. The fourth quiz has ten True-False type questions, each carrying 10 marks. What is the probability that Rahul's average internal marks for the Economics course is more than 80, given that he decides to guess randomly on the final quiz?

12/1024
11/1024
11/256
12/256

Validate

Solution:

(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 =

^ { 10 } { C } _ { 9 }

= 10 ways
II. He attempts all 10 questions correctly number of orginally ways = 2Total Number of ways =

2^10

= 1024
∴Required probability =

{10 + 1} /1024 =11/1024

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