NPTEL Introduction To Machine Learning – IITKGP Week 4 Assignment Answers 2023

## NPTEL Introduction To Machine Learning – IITKGP Week 4 Assignment Answers 2023

Questions 1-4 with the data provided below:

A spam filtering system has a probability of 0.95 to classify correctly a mail as spam and 0.10

probability of giving false positives. It is estimated that 0.5% of the mails are actual spam

mails.**Q1) Suppose that the system is now given a new mail to be classified as spam/ not-spam, what is the probability that the mail will be classified as spam?**a. 0.89575

b. 0.10425

c. 0.00475

d. 0.09950

`Answer:- b`

Q2. Find the probability that, given a mail classified as spam by the system, the mail actually being spam.

a. 0.04556

b. 0.95444

c. 0.00475

d. 0.99525

`Answer:- For Answer Click Here`

Q3. Given that a mail is classified as not spam, the probability of the mail actually being not spam

a. 0.10425

b. 0.89575

c. 0.003

d. 0.997

`Answer:- `

Q4. Find the probability that the mail is misclassified:

a. 0.90025

b. 0.09975

c. 0.8955

d. 0.1045

`Answer:- For Answer Click Here`

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:- `

Q6.

`Answer:- For Answer Click Here`

Q7. Find P (K=0| a=1, b=1).

a. 1/3

b. 2/3

C. 1/9

d. 8/9

`Answer:- `

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:- For Answer Click Here`

Q9. Suppose P(D1) = 0.4, P(D2) = 0.7 , P(SID1)=0.3 and P(S1| D1′)= 0.6. Find P(S1)

a. 0.12

b. 0.48

c. 0.36

d. 0.60

`Answer:- `

Q10. What is the Markov blanket of variable, S3

a. D1

b. D2

c. D1 and D2

d. None

`Answer:- For Answer Click Here`

Q11.

`Answer:- `

Q12.

`Answer:- `

Questions 13-14 with the data given below:

In an oral exam you have to solve exactly one problem, which might be one of three types, A. B, or C, which will come up with probabilities 30%, 20%, and 50%, respectively. During your preparation you have solved 9 of 10 problems of type A. 2 of 10 problems of type B, and 6 of 10 problems of type C.

13) What is the probability that you will solve the problem of the exam?

а. 0.61

b. 0.39

c. 0.50

d. 0.20

`Answer:- For Answer Click Here`

Q14. Given you have solved the problem, what is the probability that it was of type A?

а. 0.35

b. 0.50

c. 0.56

d. 0.44

`Answer:- `

Q15. Naive Bayes is a popular classification algorithm in machine learning. Which of the

following statements is/are true about Naive Bayes?

a. Naive Bayes assumes that all features are independent of each other, given the class.

b. It is particularly well-suited for text classification tasks, like spam detection.

c. Naive Bayes can handle missing values in the dataset without any special treatment.

d. It is a complex algorithm that requires a large amount of training data.

`Answer:- `