Probability of multiple events happening at a time (a turn)

Q1. If two people are selected at random, find the probability that both wereborn on Wednesday.
answer:
Each person has approximately one chance in seven of being born on Wednesday; hence, the probability that two people are born on Wednesday is


Q2. The probability that a person A will be alive 15 year hence is 5/7 and the probability that another person B will be alive 15 years hence is 7/9. Find the probability that both will be alive 15 year hence.
Solution:
Let event
A = when A will be alive, thus P(A)=5/7 (given)
B = when B will be alive, thus P(B)=7/9 (given)
Required probability is

Q3. A coin is tossed and a card is selected at random from a deck of 52 cards. Find the probability of getting a head and a diamond on the card.
answer:
The probability of getting a head is½, and the probability of getting adiamond is 13/52=¼; hence, the P(head and diamond).
P(H)∙P(diamond)= ½∙¼=⅛

Independent Events

Suppose box X contains 2 blue and 2 green balls, and box Y contains 1 white and 3 red balls. A ball is randomly selected from 1 each of the boxes. Determine the probability of getting “a blue ball from X and a red ball from Y”.

By illustrating the sample space on the two-dimensional grid shown, We can see that 6 of the 16 possibilities are blue from X and red from Y. Each of the outcomes is equally likely, so


In this section we look for a quicker method for finding the box); probability in such a situation.
independent events

Let’s read more explanation about Independent Events in the post Probability: Independent Events.

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