Stats 2 End Term: 22 December 2024, Set QDF1 (September 2024 term)
The IIT Madras BS Statistics for Data Science II (Stats 2) End Term paper sat on 22 Dec 2024, in the September 2024 term, set QDF1: 15 questions for 40 marks in 180 minutes. Every question is below with its answer. Take it as a timed mock test to be marked, or read it through first.
- 15
- 40
- 180 min
- 5
- 7
- 3
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Correct answer: 0.17 (accepted within ±0.03)
Question 2
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Correct answer
Question 3
Which of the following statement(s) is(are) correct?
The power of a test is the probability of rejecting the null hypothesis when it is false.
The probability of accepting the alternative hypothesis when it is true is called as level of significance.
Type I error is the probability of rejecting the null hypothesis when alternative hypothesis is false.
If the probability of making a Type II error is 0.05, the power of the test is 0.95.
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Correct answers
The power of a test is the probability of rejecting the null hypothesis when it is false.
Type I error is the probability of rejecting the null hypothesis when alternative hypothesis is false.
If the probability of making a Type II error is 0.05, the power of the test is 0.95.
Question 4
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Question 5
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Question 6
Based on the above data, answer the given subquestions.
Consider a random sample (1, 0, 1, 2, 2, 0, 1). Find the method of moments estimate of θ for the given sample. Enter the answer correct to two decimal places.
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Correct answer: 0.43 (accepted within ±0.03)
Question 7
Based on the above data, answer the given subquestions.
Consider a random sample (2, 0, 1, 1, 2, 2, 1, 1, 0, 0). Find the maximum likelihood estimate of θ for the given sample. Enter the answer correct to one decimal place.
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Correct answer: 0.3 (accepted within ±0.03)
Question 8
A company is testing a new AI-based chatbot for customer service and wants to know if it is liked by its users. Let p be the true proportion of users who would find the chatbot helpful. The team selected 30 customers randomly and asked if they found the chatbot useful. Out of these, 12 responded ‘yes’.
Based on the above data, answer the given subquestions.
Find the posterior distribution of p for a Beta [3, 2] prior.
Beta(12, 18)
Beta(15, 20)
Beta(14, 19)
Beta(20, 15)
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Correct answer
Beta(15, 20)
Question 9
A company is testing a new AI-based chatbot for customer service and wants to know if it is liked by its users. Let p be the true proportion of users who would find the chatbot helpful. The team selected 30 customers randomly and asked if they found the chatbot useful. Out of these, 12 responded ‘yes’.
Based on the above data, answer the given subquestions.
Find the posterior mean using the correct prior from the previous question. Enter the answer correct to two decimal places.
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Correct answer: 0.43 (accepted within ±0.03)
Question 10
The average battery life of smartphones for a certain model is 15 hours, with a standard deviation of 3 hours. An analyst suspects that the true average battery life is greater
than 15 hours. To test this, he takes a random sample of 100 smartphones and finds that the sample mean battery life is 17 hours.
Based on the above data, answer the given subquestions.
State the null and alternative hypotheses.
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Correct answer
Question 11
The average battery life of smartphones for a certain model is 15 hours, with a standard deviation of 3 hours. An analyst suspects that the true average battery life is greater
than 15 hours. To test this, he takes a random sample of 100 smartphones and finds that the sample mean battery life is 17 hours.
Based on the above data, answer the given subquestions.
What conclusion will you make for the given test?
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Question 12
Based on the above data, answer the given subquestions.
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Question 13
Based on the above data, answer the given subquestions.
Are X and Y independent?
Yes
No
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Correct answer
Yes
Question 14
Based on the above data, answer the given subquestions.
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Correct answer
Question 15
Based on the above data, answer the given subquestions.
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Correct answer: 1.78 (accepted within ±0.03)
