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Question (11)

QN0030788

The mean of 9 observations is 18. If one observation is removed, the mean of the remaining 8 observations becomes 17. The removed observation is

(A) 24
(B) 25
(C) 26
(D) 27

Correct Answer: C

Explanation:

Total of 9 observations = 18 × 9 = 162. Total of remaining 8 = 17 × 8 = 136. Removed observation = 162 − 136 = 26.

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Question (12)

QN0030789

The data are 8, 10, 12, 14, 16, 18 and 20. If each value is increased by 5, the median becomes

(A) 14
(B) 17
(C) 19
(D) 21

Correct Answer: C

Explanation:

Original median = 14. Adding 5 to every value increases the median by 5. New median = 19.

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Question (13)

QN0030790

A student was absent for one test. His marks were 72, 68, 81, —, 79 and 70. While calculating his average marks, the absent test should be

(A) counted as 0 marks
(B) ignored and divide only by the number of tests attended
(C) taken as 100 marks
(D) replaced by the class average

Correct Answer: B

Explanation:

A missing value is different from a score of zero. The average should be calculated using only the tests actually attended.

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Question (14)

QN0030791

The mean of the numbers 12, 18, 15, 21 and x is 18. Find x.

(A) 20
(B) 22
(C) 24
(D) 25

Correct Answer: C

Explanation:

Total = 18 × 5 = 90. Sum of known numbers = 66. Therefore, x = 90 − 66 = 24.

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Question (15)

QN0030792

Which of the following statements is always true?

(A) The mean is one of the data values.
(B) The median is always greater than the mean.
(C) The mean always lies between the minimum and maximum values.
(D) The median is always equal to the largest value.

Correct Answer: C

Explanation:

The arithmetic mean always lies between the smallest and largest values of a data set.

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Question (16)

QN0030793

The values are 6, 8, 10, 12, 14 and 16. What is the difference between the mean and the median?

(A) 0
(B) 1
(C) 2
(D) 3

Correct Answer: A

Explanation:

Mean = (6 + 8 + 10 + 12 + 14 + 16) ÷ 6 = 11. Median = (10 + 12) ÷ 2 = 11. Difference = 0.

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Question (17)

QN0030794

A double-bar graph is prepared to compare the monthly sales of two shops. Which feature makes the comparison easier?

(A) Both bars of the same category are drawn side by side using the same scale.
(B) Each bar has a different scale.
(C) The bars are drawn randomly.
(D) Only one colour is used for all bars.

Correct Answer: A

Explanation:

A double-bar graph uses the same scale and places bars side by side for easy comparison.

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Question (18)

QN0030795

The mean of 6 numbers is 15. If each number is multiplied by 2, the new mean is

(A) 15
(B) 17
(C) 30
(D) 60

Correct Answer: C

Explanation:

Multiplying every observation by 2 also doubles the mean. Hence, the new mean = 30.

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Question (19)

QN0030796

Which statement best explains why a dot plot is useful?

(A) It helps identify the spread, clusters and repeated values in data.
(B) It always gives the mean directly.
(C) It shows only the largest value.
(D) It can represent only five observations.

Correct Answer: A

Explanation:

A dot plot displays each data value, making it easy to observe variability, clustering and repeated values.

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Question (20)

QN0030797

A survey records the number of books read by students as 2, 3, 5, 6, 7, 8 and 39. Which measure gives a better representative value for this data?

(A) Mean, because it is affected by the large value.
(B) Median, because it is less affected by the outlier.
(C) Range, because it gives the middle value.
(D) Maximum, because it is the largest observation.

Correct Answer: B

Explanation:

The value 39 is an outlier. The median (6) is less affected by the outlier and better represents the centre of the data.

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Question (11)

The mean of 9 observations is 18. If one observation is removed, the mean of the remaining 8 observations becomes 17. The removed observation is

Explanation:

Link:

Question (12)

The data are 8, 10, 12, 14, 16, 18 and 20. If each value is increased by 5, the median becomes

Explanation:

Link:

Question (13)

A student was absent for one test. His marks were 72, 68, 81, —, 79 and 70. While calculating his average marks, the absent test should be

Explanation:

Link:

Question (14)

The mean of the numbers 12, 18, 15, 21 and x is 18. Find x.

Explanation:

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Question (15)

Which of the following statements is always true?

Explanation:

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Question (16)

The values are 6, 8, 10, 12, 14 and 16. What is the difference between the mean and the median?

Explanation:

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Question (17)

A double-bar graph is prepared to compare the monthly sales of two shops. Which feature makes the comparison easier?

Explanation:

Link:

Question (18)

The mean of 6 numbers is 15. If each number is multiplied by 2, the new mean is

Explanation:

Link:

Question (19)

Which statement best explains why a dot plot is useful?

Explanation:

Link:

Question (20)

A survey records the number of books read by students as 2, 3, 5, 6, 7, 8 and 39. Which measure gives a better representative value for this data?

Explanation:

Link:

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