Statistics · NDA previous year questions

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2020 8 questions

Q1012020 · 6 Sept 2020
The numbers 4 and 9 have frequencies $x$ and $(x - 1)$ respectively. If their arithmetic mean is 6, then what is the value of $x$ ?
1. A.2
2. B.3
3. C.4
4. D.5
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Answer: B
Q1052020 · 6 Sept 2020
A data set of $n$ observations has mean $2 M$ , while another data set of $2 n$ observations has mean $M$ . What is the mean of the combined data sets?
1. A. $M$
2. B. $\frac{3 M}{2}$
3. C. $\frac{2 M}{3}$
4. D. $\frac{4 M}{3}$
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Answer: D
Q1062020 · 6 Sept 2020
Directions for the following three (03) items: Read the following information and answer the three items that follow: $Marks 10 - 20 20 - 30 30 - 40 40 - 50 50 - 60 60 - 70 Number of students (Physics) 81130261510 Number of students (Mathematics) 10213815106$ The difference between number of students under Physics and Mathematics is largest for the interval
1. A. $20 - 30$
2. B. $30 - 40$
3. C. $40 - 50$
4. D. $50 - 60$
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Answer: C
Q1072020 · 6 Sept 2020
Directions for the following three (03) items: Read the following information and answer the three items that follow: $Marks 10 - 20 20 - 30 30 - 40 40 - 50 50 - 60 60 - 70 Number of students (Physics) 81130261510 Number of students (Mathematics) 10213815106$ Consider the following statements: 1. Modal value of the marks in Physics lies in the interval $30 - 40$ . 2. Median of the marks in Physics is less than that of marks in Mathematics. Which of the above statements is/are correct?
1. A.1 only
2. B.2 only
3. C.Both 1 and 2
4. D.Neither 1 nor 2
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Answer: A
Q1082020 · 6 Sept 2020
Directions for the following three (03) items: Read the following information and answer the three items that follow: $Marks 10 - 20 20 - 30 30 - 40 40 - 50 50 - 60 60 - 70 Number of students (Physics) 81130261510 Number of students (Mathematics) 10213815106$ What is the mean of marks in Physics?
1. A.38.4
2. B.39.4
3. C.40.9
4. D.41.6
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Answer: C
Q1092020 · 6 Sept 2020
What is the standard deviation of the observations $- 6, - 5, - 4, - 1, 1, 4, 5, 6$ ?
1. A. $2$
2. B.2
3. C. $22$
4. D.4
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Answer: B
Q1122020 · 6 Sept 2020
The arithmetic mean of 100 observations is 40. Later, it was found that an observation '53' was wrongly read as '83'. What is the correct arithmetic mean?
1. A.39.8
2. B.39.7
3. C.39.6
4. D.39.5
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Answer: B
Q1172020 · 6 Sept 2020
Let $X$ and $Y$ represent prices (in ₹) of a commodity in Kolkata and Mumbai respectively. It is given that $\overset{ˉ}{X} = 65$ , $\overset{ˉ}{Y} = 67$ , $σ_{X} = 2.5$ , $σ_{Y} = 3.5$ and $r (X, Y) = 0.8$ . What is the equation of regression of $Y$ on $X$ ?
1. A. $Y = 0.175 X - 5$
2. B. $Y = 1.12 X - 5.8$
3. C. $Y = 1.12 X - 5$
4. D. $Y = 0.17 X + 5.8$
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Answer: B