Find Probability of an Event Examples :
Here we are going to see some practice questions on probability.
Question 1 :
A company manufactures 10000 Laptops in 6 months. Out of which 25 of them are found to be defective. When you choose one Laptop from the manufactured, what is the probability that selected Laptop is a good one.
Number of laptops n(S) = 10000
Number of defective lap top = 25
Let "A" be the event of choosing good laptop.
Number of good laptop = 10000 - 25
n(A) = 9975
p(A) = n(A)/n(S)
p(A) = 9975/10000
p(A) = 0.9975
Question 2 :
In a survey of 400 youngsters aged 16-20 years, it was found that 191 have their voter ID card. If a youngster is selected at random, find the probability that the youngster does not have their voter ID card.
Total number of youngster n(S) = 400
Let "A" be the event of choosing youngster does not have ID card
= 400 - 191
n(A) = 209
P(A) = n(A)/n(S)
P(A) = 209/400
Question 3 :
The probability of guessing the correct answer to a certain question is x/3 . If the probability of not guessing the correct answer is x/5, then find the value of x.
P(A) = Probability of getting correct answer
p(B) = Probability of getting not guessing correct answer
P(A) + p(B) = 1
(x/3) + (x/5) = 1
(5x + 3x)/15 = 1
8x = 15
x = 15/8
Question 4 :
If a probability of a player winning a particular tennis match is 0.72. What is the probability of the player loosing the match?
Let "A" be event of winning a game. A bar be the event of lossing the game.
p(A) + p(A bar) = 1
0.72 + p(A bar) = 1
p(A bar) = 1 - 0.72
p(A bar) = 0.28
Question 5 :
1500 families were surveyed and following data was recorded about their maids at homes
A family is selected at random. Find the probability that the family selected has (i) Both types of maids (ii) Part time maids (iii) No maids
Total number of families n(S) = 1500
Let "A" be the event of selecting maid of both types.
n(A) = 250
p(A) = n(A)/n(S)
p(A) = 250/1500
p(A) = 1/6
(ii) Part time maids
Let "B" be the event of selecting maid of part time
n(B) = 8600
p(B) = n(B)/n(S)
p(B) = 860/1500
p(B) = 43/75
(iii) No maids
Number of families selected maid = 860 + 370 + 250
n(C) = 1500 - 1480
n(C) = 20
P(C) = n(C)/n(S)
p(C) = 1/75
After having gone through the stuff given above, we hope that the students would have understood, "Find Probability of an Event Examples"
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