Class 8, Maths, Chapter 5, Exercise 5.3, Solutions
Q.1. List the outcomes you can see in these experiments.
(a) Spinning a wheel
(b) Tossing two coins together
Ans: (a) Outcomes = A, B, C, D
(b) Tossing two coins together
Q.2. When a die is thrown, list the outcomes of an event of getting
(i) (a) a prime number (b) not a prime number.
(ii) (a) a number greater than 5 (b) a number not greater than 5.
Ans:
(i) (a) a prime number = 2,3,5
(b) not a prime number = 1,4,6
(ii) (a) a number greater than 5 = 6
(b) a number not greater than 5 = (1,2,3,4,5)
Q.3. Find the.
(a) Probability of the pointer stopping on D in (Question 1-(a))?
(b) Probability of getting an ace from a well shuffled deck of 52 playing cards?
(c) Probability of getting a red apple. (See figure below)
Ans: (a) total number of evets or parts = 5
Number of favourable outcomes = 1
$=\frac{Favourable\,\,outcome}{Total\,\,parts}=\frac{1}{5}$
(b) total number of evets = 52
Number of favourable outcomes = 4 (there are 4 aces in a pack of cards)
$=\frac{Favourable\,\,outcome}{Total outcomes\,\,}=\frac{4}{52}=\frac{1}{13}$
(c) total number of evets = 6
Number of favourable outcomes = 4
$=\frac{Favourable\,\,outcome}{Total events\,\,}=\frac{4}{7}$
Q.4. Numbers 1 to 10 are written on ten separate slips (one number on one slip), kept in a box and mixed well. One slip is chosen from the box without looking into it. What is the probability of .
(i) getting a number 6?
(ii) getting a number less than 6?
(iii) getting a number greater than 6?
(iv) getting a 1-digit number?
Ans:
Total number of events = 10
(i) Getting a number 6: $=\frac{Favourable\,\,outcome}{Total\,\,}=\frac{1}{10}$
(ii) getting a number less than 6: $=\frac{Favourable\,\,outcome}{Total\,\,}=\frac{5}{10}=\frac{1}{2}$
(iii) getting a number greater than 6 : $=\frac{Favourable\,\,outcome}{Total\,\,}=\frac{4}{10}=\frac{2}{5}$
(iv) getting a 1-digit number: $=\frac{Favourable\,\,outcome}{Total\,\,}=\frac{9}{10}$
Q.5. If you have a spinning wheel with 3 green sectors, 1 blue sector and 1 red sector, what is the probability of getting a green sector? What is the probability of getting a non blue sector?
Ans:
Total number of events = 5 (because there are total 5 sectors)
(i) probability of getting a green sector $=\frac{Favourable\,\,outcome}{Total\,\,}=\frac{3}{5}$
(ii) probability of getting a Non – Blue sector $=\frac{Favourable\,\,outcome}{Total\,\,}=\frac{3+1}{5}=\frac{4}{5}$
Q.6. Find the probabilities of the events given in Question 2.
Ans: In throwing a die, possible outcomes of the number appearing on top face = 1, 2, 3, 4, 5, 6
Prime numbers in the outcomes = 2, 3, 5
Non-prime numbers in the outcomes = 1, 4, 6
Numbers greater than 5 = 6
Numbers not greater than 5(including 5) = 1, 2, 3, 4, 5
(i) (a) a prime number $=\frac{Favourable\,\,outcome}{Total\,\,}=\frac{3}{6}=\frac{1}{2}$
(b) not a prime number $=\frac{Favourable\,\,outcome}{Total\,\,}=\frac{3}{6}=\frac{1}{2}$
(ii) (a) a number greater than 5 $=\frac{Favourable\,\,outcome}{Total\,\,}=\frac{1}{6}$
(b) a number not greater than 5 $=\frac{Favourable\,\,outcome}{Total\,\,}=\frac{5}{6}$