Latest TCS Aptitude Question SOLUTION: A student is given a true - false exam with 10 questions. If he gets 8 or more correct answers he passes the exam. Given that he guesses at the answer to each question, what is the

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A student is given a true - false exam with 10 questions. If he gets 8 or more correct answers he passes the exam. Given that he guesses at the answer to each question, what is the probability that he passes the exam ?

Asked In TCS payel (9 years ago)

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kratika  (9 years ago)

To pass the exam one should have 8,9 or 10 correct answers

There are 1024 ways to answer the questions 2^10 = 1024 ways.

There are 10C8 ways to get 8 out of 10 correct
10C8 = 10 x 9 / 2! = 45 ways

There are 10C9 ways to get 9 out of 10 correct
10C9 = 10 / 1! = 10 ways

There are 10C10 ways to get 10 out 10 correct
10C10 = 1 way

45 + 10 + 1 = 56 good outcomes out of 1024 possible outcomes.

56 / 1024 = 0.05469

Answer:
Approx. 5.47%

Is this solution Helpfull? Yes (44) | No (2)  

sravya  (9 years ago)

For every question we have 2 options true and false.
so for a question to be correct the probability is 1/2.
possible answers are {8,9,10}
so probability is (1/2^8)+(1/2^9)+(1/2^10)=7/2^10.

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sanjana  (9 years ago)

can u tell me how to post questio.i want to post my tcs questions

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kratika  (9 years ago)

payel every question has two ways to be answered as either true or as false
So as for one question there is 2 ways
So for 10 questions 2X2X2X2X2X2X2X2X2X2 = 2^10 ways

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rahul gera  (9 years ago)

7/2^7
10c8+10c9+10c10/2^10

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sayalee bhusari  (9 years ago)

the no of ways he can answer 10 questions is= 2^10
the no of ways of getting 8 of them right =2^8
the probability of passing=2^8/2^10 =1/4

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virendra tiwari  (9 years ago)

32^10,,,total 2^10 and passinf prob is 0nly 3,if he ans 8,9 or 10 correcrt soooo,ans

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Vedant Shete  (9 years ago)

the no of ways he can answer 10 questions = 2^10
the no of ways of passing the test(by obtaining either 8 or 9 or 10 correct)= 2^3
The probability of passing = 2^3/2^10 = 1/2^7 = 1/128

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Monika Parmar  (9 years ago)

X=he passes exam if he get 8,9or 10 marks
then P(x)=3/10=.3

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payel  (9 years ago)

kartika cant get your logic.total possible outcome=2^10??why?pls explain the logic.

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