The addition theorem of probability for two events A and B states that P(A ∪ B) = P(A) + P(B) - P(A ∩ B). This formula accounts for: MCQ with Answer and Explanation

The addition theorem of probability for two events A and B states that P(A ∪ B) = P(A) + P(B) - P(A ∩ B). This formula accounts for:
A. The conditional probability of A given B
B. The independence of events
C. The double-counting of outcomes common to both A and B
D. The complement of event A
Answer: Option C
Solution (By JKSSB Mock Tests)
Subtracting P(A ∩ B) corrects for the fact that outcomes in the intersection are counted twice when adding P(A) and P(B), ensuring accurate probability calculation for the union.

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Practice More Statistics Questions

Question #1
Perinatal Mortality Rate includes stillbirths from which gestational age?
A. 20 weeks
B. 32 weeks
C. 28 weeks
D. 24 weeks

Correct Answer: Option C


Explanation:
Per WHO definition, perinatal mortality includes late fetal deaths (stillbirths) from 28 completed weeks of gestation and early neonatal deaths (first 7 days), capturing risks around birth.

This question belongs to: Accountancy and Statistics Statistics
Question #2
If P(A) = 0.6, P(B) = 0.7, and P(A ∪ B) = 0.9, then P(A ∩ B) is:
A. 0.2
B. 0.4
C. 0.3
D. 0.5

Correct Answer: Option B


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.

This question belongs to: Accountancy and Statistics Statistics
Question #3
If the price index for 2020 with base 2015 is 125, and for 2025 with base 2020 is 120, the index for 2025 with base 2015 using chain method is:
A. 140
B. 145
C. 150
D. 125 × 1.2 = 150

Correct Answer: Option D


Explanation:
Chain index = 125 × (120/100) = 125 × 1.2 = 150.

This question belongs to: Accountancy and Statistics Statistics