Samacheer Kalvi 9th Maths Solutions Chapter 9 Probability Ex 9.1

Samacheer Kalvi 9th Maths Solutions Chapter 9 Probability Ex 9.1

Tamilnadu Samacheer Kalvi 9th Maths Solutions Chapter 9 Probability Ex 9.1

Question 1.
You are walking along a street. If you just choose a stranger crossing you, what is the probability that his next birthday will fall on a Sunday?
Solution:
Days in a week (S) = {Sunday, Monday, Tuesday, Wednesday, Thursday, Friday, Saturday}
n( S) = 7
∴ No. of days in week = 7
Event of selecting Sunday (A) = {Sunday}
n(A) = 1
∴ Probability of selecting Sunday = n(A)/n(S)=1/7

Question 6.
Two dice are rolled, find the probability that the sum is
(i) equal to 1
(ii) equal to 4
(iii) less than 13
Solution:
When two dice are rolled Sample space

Question 7.
A manufacturer tested 7000 LED lights at random and found that 25 of them were defective. If a LED light is selected at random, what is the probability that the selected LED light is a defective one.
Solution:
n(S) = 7000 S – Total no. of lights.
n(A) = 25 A – Defective ones.

Question 8.
In a football match, a goalkeeper of a team can stop the goal, 32 times out of 40 attempts tried by a team. Find the probability that the opponent team can convert the attempt into a goal.
Solution:
Total no. of attempts n(S) = 40
Total no. of attempts by A team n(A) = 32
Total no. of attempts by the opponent team B = n(B) = 40 – 32 = 8

Question 9.
What is the probability that the spinner will not land on a multiple of 3?
Solution:
Total no. of choices n(S) = 8
Total no. of multiples of 3 A = {3, 6}
n(A) = 2
Event of non-multiples of 3B = {1, 2, 4, 5, 7, 8}
n(B) = 6

Question 10.
Frame two problems in calculating probability, based on the spinner shown here.

Solution:
(i) What is the probability that the spinner will land on an even number?
(ii) What is the probability that the spinner will not land on a prime number.