NPTEL Introduction To Machine Learning IITKGP ASSIGNMENT 4

These are solutions for NPTEL Introduction To Machine Learning IITKGP ASSIGNMENT 4 Week 4

Course Name: Introduction To Machine Learning IITKGP

Link to Enroll: Click Here

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Q1) A man is known to speak the truth 2 out of 3 times. He throws a die and reports that the number obtained is 4. Find the probability that the number obtained is actually 4 :
A. 2/3
B. 3/4
C. 5/22
D. 2/7

Answer: D. 2/7

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Q2) Consider the following graphical model, mark which of the following pair of random variables are independent given no evidence?
A. a,b
B. c,d
C. e,d
D. c,e

Answer: A. a,b

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These are solutions for NPTEL Introduction To Machine Learning IITKGP ASSIGNMENT 4 Week 4

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Q3) Two cards are drawn at random from a deck of 52 cards without replacement. What is the probability of drawing a 2 and an Ace in that order?
A. 4/51
B. 1/13
C. 4/256
D. 4/663

Answer: D. 4/663

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Q4) Consider the following Bayesian network. The random variables given in the model are modeled as discrete variables (Rain = R, Sprinkler = S and Wet Grass = W) and the corresponding probability values are given below.
P(R) = 0.1 P(S) = 0.2 P(W | R, S) P(WIR, P(WIR, P(WI-R.
Calculate P(S | W, R).
A. 1
B. 0.5
C. 0.22
D. 0.78

Answer: C. 0.22

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These are solutions for NPTEL Introduction To Machine Learning IITKGP ASSIGNMENT 4 Week 4

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Q5) What is the naive assumption in a Naive Bayes Classifier?
A. All the classes are independent of each other
B. All the features of a class are independent of each other
C. The most probable feature for a class is the most important feature to be considered for classification
D. All the features of a class are conditionally dependent on each other.

Answer: B. All the features of a class are independent of each other

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Q6) A drug test (random variable T) has 1% false positives (i.e., 1% of those not taking drugs show positive in the test), and 5% false negatives (i.e., 5% of those taking drugs test negative). Suppose that 2% of those tested are taking drugs. Determine the probability that somebody who tests positive is actually taking drugs (random variable D).
A. 0.66
B. 0.34
C. 0.50
D. 0.91

Answer: A. 0.66

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These are solutions for NPTEL Introduction To Machine Learning IITKGP ASSIGNMENT 4 Week 4

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Q7) It is given that P(A|B) = A. ½ B. 2/3 and P(A/B) = 1/4. Compute the value of P(B|A).
A. 1/2
B. 2/3
C. 3/4
D. Not enough information.

Answer: A. 1/2

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Q8) What is the joint probability distribution in terms of conditional probabilities?
A. P(D1)*P(D2|D1) * P(S1|D1) * P(S2|D1) * P(S3|D2)
B. P(D1)*P(D2) * P(S1|D1) * P(S2|D1) * P(S3|D1, D2)
C. P(D1)P(D2) P(S1|D2)P(S2|D2) P(S3|D2)
D. P(D1)P(D2) P(S1|D1) * P(S2|D1, D2)* P(S3|D2)

Answer: D. P(D1)P(D2) P(S1|D1) * P(S2|D1, D2)* P(S3|D2)

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These are solutions for NPTEL Introduction To Machine Learning IITKGP ASSIGNMENT 4 Week 4

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Q9) Suppose P(D1) = 0.5, P(D2)=0.6, P(S1|D1)=0.4 and P(S1| D1′)= 0.6. Find P(S1)
A. 0.14
B. 0.36
C. 0.50
D. 0.66

Answer: B. 0.36

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Q10) In a Bayesian network a node with only outgoing edge(s) represents
A. a variable conditionally independent of the other variables.
B. a variable dependent on its siblings.
C. a variable whose dependency is uncertain.
D. None of the above.

Answer: A. a variable conditionally independent of the other variables.

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These are solutions for NPTEL Introduction To Machine Learning IITKGP ASSIGNMENT 4 Week 4

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