## Tamilnadu Samacheer Kalvi 9th Maths Solutions Chapter 9 Probability Ex 9.2

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.
Solution:
Total n(S) = 10,000
Defective n( A) = 25 No. of good laptops = 1000 – 25
n(B) = 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.
Solution:
No. of youngsters n(S) = 400
No. of youngsters having voter id n(A) = 191
No. of youngsters do not have their voter id n(B) = 400 – 191 = 209 Question 3.
The probability of guessing the correct answer to a certain question is $$\frac{x}{3}$$. If the probability of not guessing the correct answer is $$\frac{x}{5}$$, then find the value of x.
Solution: 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?
Solution:
P(A) = 0.72
P(A’) = 1 – 0.72 = 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
Solution:
n(S) = 1500 (Total families)
n(A) = 860 (Part time maids)
n(B) = 370 (Only full time)
n(A∩B) = 250 (Both)  Total families n(S) = 1500
No. of families have maids = 860 + 250 + 370 = 1480
No. of families do not have maids = 1500 – 1480
n( A) = 20  