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## 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