If the arithmetic mean of 5 numbers is 20, and the arithmetic mean of another 3 numbers is 28, the combined mean of all 8 numbers is: MCQ with Answer and Explanation

If the arithmetic mean of 5 numbers is 20, and the arithmetic mean of another 3 numbers is 28, the combined mean of all 8 numbers is:

A. 25

B. 23

C. 24

D. 22

Answer: Option B

Combined mean = (5×20 + 3×28) / (5+3) = (100 + 84) / 8 = 184 / 8 = 23. This formula weights each group's mean by its size.

This question belongs to: Accountancy and Statistics Statistics

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Question #1 Report Error

A box contains 3 defective and 7 non-defective items. Two items are selected at random. The probability that exactly one is defective is:

A. 7/15

B. 1/5

C. 21/45

D. 14/45

Correct Answer: Option A

Explanation:
Total C(10,2)=45. Favorable: 3×7=21. Probability=21/45=7/15.

This question belongs to: Accountancy and Statistics Statistics

Question #2 Report Error

Two events are mutually exclusive if they:

A. Cannot occur together

B. Can occur together

C. Always occur together

D. Have equal probabilities

Correct Answer: Option A

Explanation:
Mutually exclusive events have no common outcome; P(A∩B) = 0.

This question belongs to: Accountancy and Statistics Statistics

Question #3 Report Error

The denominator of Crude Death Rate is:

A. Number of women

B. Mid-year total population

C. Number of live births

D. Number of elderly

Correct Answer: Option B

Explanation:
CDR = (Total deaths / Mid-year population) × 1000.

This question belongs to: Accountancy and Statistics Statistics