The combined mean of two groups is 55, with n₁=40, mean₁=50. If n₂=60, mean₂ is: MCQ with Answer and Explanation

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The combined mean of two groups is 55, with n₁=40, mean₁=50. If n₂=60, mean₂ is:

A. 58.33

B. 59

C. 60

D. 57.5

Answer: Option A

Solution (By JKSSB Mock Tests)

55 = (40×50 + 60×x) / 100 → 2000 + 60x = 5500 → 60x = 3500 → x = 58.33.

This question belongs to: Accountancy and Statistics Statistics

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Practice More Statistics Questions

Question #1

If P(A) = 0.6, P(B) = 0.7, and P(A ∪ B) = 0.9, then P(A ∩ B) is:

A. 0.5

B. 0.2

C. 0.3

D. 0.4

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Correct Answer: Option D

Explanation:
By addition theorem: P(A∪B) = P(A) + P(B) - P(A∩B) → 0.9 = 0.6 + 0.7 - P(A∩B) → P(A∩B) = 1.3 - 0.9 = 0.4.

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Question #2

The geometric mean is preferred for averaging:

A. Test scores

B. Heights of students

C. Temperatures

D. Percentage growth rates

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Correct Answer: Option D

Explanation:
Geometric mean is suitable for averaging ratios and rates of change over time.

This question belongs to: Accountancy and Statistics Statistics

Question #3

The cumulative frequency curve is also known as:

A. Frequency polygon

B. Bar chart

C. Ogive

D. Histogram

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Correct Answer: Option C

Explanation:
An ogive is a graph of cumulative frequencies plotted against the upper class boundaries (less than type) or lower boundaries (more than type).

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