CBSE NCERT Solutions for Class 8 Chapter 5

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CBSE NCERT Solutions for Class 8 Maths Chapter 5:

Question-1:

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 than5 (b) a number not greater than5

Solution:

(i) (a) Outcomes of event of getting a prime number are 2, 3 and 5.
(b) Outcomes of event of not getting a prime number are 1, 4 and 6.
(ii) (a) Outcomes of event of getting a number greater than 5 is 6.
(b) Outcomes of event of not getting a number greater than 5 are 1, 2, 3, 4 and 5.

Question-2:

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

Solution:

(i) Outcome of getting a number 6 from ten separate slips is one. Therefore, probability of getting a number 1/10
(ii) Numbers less than 6 are 1, 2, 3, 4 and 5 which are five. So there are 5 outcomes. Therefore,
probability of getting a number less than 6 = 5/10 = ½
(iii) Number greater than 6 out of ten that are 7, 8, 9, 10.So there are 4 possible outcomes.
Therefore probability of getting a number greater than 6 = 4/10 = 2/5
(iv) One digit numbers are 1, 2, 3, 4, 5, 6, 7, 8, 9 out of ten . Therefore probability of getting a 1-digit number = 9/10

Question-3:

Find the probability of the events given 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

Solution:

When a die is thrown, there are total six outcomes, i.e., 1, 2, 3, 4, 5 and 6.
(i) (a) 2, 3, 5 are prime numbers. So there are 3 outcomes out of 6.
Therefore, probability of getting a prime number = 3/6 = ½
(b) 1, 4, 6 are not the prime numbers. So there are 3 outcomes out of 6.
Therefore, probability of getting a prime number =3/6 = ½
(ii) (a) Only 6 is greater than 5. So there is one outcome out of 6.
There. Probability of getting a number greater than 5 = 1/6
(b) Numbers not greater than 5 are 1, 2, 3, 4 and 5. So there are 5 outcomes out of 6. Therefore, probability of not getting a number greater than 5 = 5/6