Probability - Study Mode

[#1] Binomial distribution is negatively skewed when
Correct Answer

(B) p > $$frac{{1}}{{2}}$$

Explanation

Solution: p > $$frac{{1}}{{2}}$$ If p < 0.5, then the distribution is positively skewed. If p > 0.5, the distribution is negatively skewed

[#2] A speaks truth in 75% cases and B in 80% of cases. In what percentage of cases they contradict each other in narrating the same incident?
Correct Answer

(C) 35%

Explanation

Solution: Probability that A is telling the truth P(A) = $$frac{{75}}{{100}}$$ = $$frac{{3}}{{4}}$$ Probability that B is telling the truth P(B) = $$frac{{80}}{{100}}$$ = $$frac{{4}}{{5}}$$ Probability that A is lying P(A’) = 1 - $$frac{{75}}{{100}}$$ = $$frac{{25}}{{100}}$$ = $$frac{{1}}{{4}}$$ Probability that B is lying P(B’) = 1 - $$frac{{80}}{{100}}$$ = $$frac{{20}}{{100}}$$ = $$frac{{1}}{{5}}$$ Contradiction means either of A telling truth and B lying Or B telling truth and A lying P(Contradiction) = P(A) × P(B’) + P(A’) × P(B) = $$frac{{3}}{{4}}$$ × $$frac{{1}}{{5}}$$ + $$frac{{1}}{{4}}$$ × $$frac{{4}}{{5}}$$ = $$frac{{7}}{{20}}$$ $$frac{{7}}{{20}}$$ is equal to 35 %.

[#3] If the occurrence of one event means that another cannot happen, then the events are
Correct Answer

(D) Mutually Exclusive

Explanation

Solution: Two events are mutually exclusive if they (both of them) cannot occur together.

[#4] A listing of the possible outcomes of an experiment and their corresponding probability is called
Correct Answer

(D) Probability distribution

Explanation

Solution: Probability distribution is listing of the all possible outcomes from an experiment with their associated probability for each outcome.

[#5] Which of the following is not a correct statement about a probability.
Correct Answer

(D) It is the collection of several experiments

Explanation

Solution: Probability is measure of uncertainty its not collection of several experiments.