# Selina Solutions Concise Maths Class 8 Chapter 23: Probability

Selina Solutions Concise Maths Class 8 Chapter 23 Probability is one of the important chapters as it would be continued in higher levels of education. For this purpose, it is necessary for the students to understand each and every concept covered in this chapter clearly. Students will be able to cross check their answers while solving the textbook questions and understand the topics which they are weak at. Here, the students can download the ICSE Selina Solutions Class 8 Maths Chapter 23 Probability PDF, from the link which is given below.

Probability is a branch of Mathematics which is concerned with how likely an event is to occur or if that proposition is true. Students who aspire to perform well in the Class 8 exams are advised to solve the problems on a daily basis. It will also help them to clear their queries on time without any confusion.

## Access Selina Solutions Concise Maths Class 8 Chapter 23: Probability

Exercise

QuestionÂ 1

A die is thrown, find the probability of getting:

Â (i) A prime numberÂ

Solution:-

Â A die has six numbers:Â 1, 2, 3, 4, 5, 6

No. of possible outcomesÂ =6

We know that

Number of favorable outcomesÂ =Â a primeÂ numberÂ = 1, 3, 5Â which areÂ 3Â in numbersÂ (Formula)

Here

Â (ii) A number greater than 4Â

Solution:-

We know that

No. of favorable outcome = GreaterÂ than four i.e. two numberÂ 5Â andÂ 6

Here

(iii) A number not greater than 4.Â

Solution:-

We know that

Number of favorable outcomeÂ =Â not greater thanÂ 4Â or numbers will beÂ 1,2,3,4Â whichÂ areÂ 4Â in numbers

Here

QuestionÂ 2.Â

A coin is tossed. What is the probability of getting

(i) A tail?

Solution:-

Â On tossing a coin once,

No. of possible outcomeÂ =2

(i) Favorable outcome getting a tailÂ =1

No. of favorable outcomeÂ =2

We know that

Solution:-

Favorable outcome getting a headÂ  =1

No. of possible outcomeÂ =2

We know that

Question 3.Â

Â A coin is tossed twice. Find the probability of getting:Â

Solution:-

Possible number of favorable outcomesÂ =2 Â (i.e.Â THÂ andÂ HT)

Total number of possible outcomesÂ =4

We know that

(ii) Exactly one tailÂ

Solution:-

Exactly one tail

Possible number of favorable outcomesÂ =2 (i.e. TH andÂ HT)

Total number of possible outcomesÂ =4

We know that

(iii) Two tails

Solution:-

Possible number of favorable outcomesÂ =1 Â (i.e. TT)

Total number of possible outcomesÂ =4

We know that

Solution:-

Possible number of favorable outcomesÂ =1 (i.e. HH)

Total number of possible outcomes = 4

So we get

P (E) = Â¼

QuestionÂ 4.Â

A letter is chosen from the word â€˜PENClLâ€™ what is the probability that the letter chosen is a consonant?

Solution:-

We know that

Total no. of letters in the word â€˜PENCILâ€™Â =6

Total Number of Consonant = â€˜PNCLâ€™ i.e,Â 4

Here

Question 5.Â

A bag contains a black ball, a red ball and a green ball, all the balls are identical in shape and size. A ball isÂ drawn from the bag without looking into it. What is the probability that the ball drawn is:

(i) a red ball

Solution:-

Total number of possible outcomesÂ =3

P (E) = 1/3

Â (ii) Not a red ballÂ

Solution:-

No. of favorable outcomes

P (E) = 2/3

Â (iii) A white ball.Â

Solution:-

No. of favorable outcomesÂ =0

P (E) = 0/3 = 0

Question 6.Â

In a single throw of a die, find the probability of getting a number

(i) Greater thanÂ 2

Solution:-

Â A die has six numbersÂ =1, 2, 3,4,5,6

No. of possible outcomesÂ =6

QuestionÂ 7.

AÂ bagÂ containsÂ 3Â white,Â 5Â blackÂ andÂ 2Â redÂ balls,Â allÂ ofÂ theÂ sameÂ shapeÂ andÂ size.

AÂ ballÂ isÂ drawnÂ fromÂ theÂ bagÂ withoutÂ lookingÂ intoÂ it,Â findÂ theÂ probabilityÂ thatÂ theÂ ballÂ drawnÂ is:

(i)Â aÂ blackÂ ball.

(ii)Â aÂ redÂ ball.

(iii)Â aÂ whiteÂ ball.

(iv)Â notÂ aÂ redÂ ball.

(v)Â notÂ aÂ blackÂ ball.

Solution:-

InÂ aÂ bag,Â 3Â ballsÂ areÂ white

2Â ballsÂ areÂ red

5Â ballsÂ areÂ black

TotalÂ numberÂ ofÂ ballsÂ =3+2+5=10

(i)Â NumberÂ ofÂ possibleÂ outcomesÂ ofÂ oneÂ blackÂ ballÂ =10Â andÂ numberÂ ofÂ favorableÂ outcomeÂ ofÂ oneÂ blackÂ ballÂ =5

We know that

QuestionÂ 8

InÂ aÂ singleÂ throwÂ ofÂ aÂ die,Â findÂ theÂ probabilityÂ thatÂ theÂ number:

(i)Â WillÂ beÂ anÂ evenÂ number.

(ii)Â willÂ beÂ anÂ oddÂ number.

(iii)Â willÂ notÂ beÂ anÂ evenÂ number.

Solution:-

AÂ dieÂ hasÂ sixÂ numbers:Â  1, 2, 3, 4, 5, 6

NumberÂ ofÂ possibleÂ outcomeÂ =6

(i)Â NumberÂ ofÂ favorableÂ outcomeÂ =Â anÂ evenÂ numberÂ i.e.Â  2, 4, 6Â whichÂ areÂ 3Â inÂ numbers

QuestionÂ 9.Â

InÂ aÂ singleÂ throwÂ ofÂ aÂ die,Â findÂ theÂ probabilityÂ ofÂ getting:

(i)Â 8

(ii)Â aÂ numberÂ greaterÂ thanÂ 8

(iii)Â aÂ numberÂ lessÂ thanÂ 8

Solution:-

OnÂ aÂ dieÂ theÂ numbersÂ areÂ 1, 2, 3, 4, 5, 6Â  i.e, six.

NumberÂ ofÂ possibleÂ outcomeÂ =6

(i)Â NumberÂ ofÂ favorableÂ outcomeÂ =0

(âˆµ8Â isÂ notÂ possible)

We know that

QuestionÂ 10.Â

WhichÂ ofÂ theÂ followingÂ cannotÂ beÂ theÂ probabilityÂ ofÂ anÂ event?

Solution:-

TheÂ probabilityÂ ofÂ anÂ eventÂ cannotÂ be

(ii)Â 3.8Â i.e., theÂ probabilityÂ ofÂ anÂ evenÂ cannotÂ exceedÂ 1.

(iv)Â i.e.,Â -0.8

(vi)Â âˆ’2/5, becauseÂ probabilityÂ ofÂ anÂ evenÂ canÂ neverÂ beÂ lessÂ thanÂ 1.

Question 11.

A bag contains six identical black balls. A child withdraws one ball from the bag without looking into it. What is the probability that he takes out:

(i) a white ball,

(ii) a black ball

Solution:-

There are 6 black balls in a bag

Number of possible outcome =6

(i) A white ball

As there is no white ball in the bag

Probability is zero (0) = or P(E)=0

(ii) a black ball

Number of favorable outcome =1

We know that

Question 12.

Three identical coins are tossed together. What is the probability of obtaining?

Solution:-

Total outcomes =8

i.e. (H,H,H),(H,H,T),(H,T,H),(T,T,T),(T,H,H),(T,T,H),(H,T,T),(T,H,T)

(i) Favorable outcome= i.e. (H,H,H)

Question 13.

A book contains 92 pages. A page is chosen at random. What is the probability that the sum of the digits in the page number is 9?

Solution:-

Number of pages of the book =92 which are from 1 to 92

Number of possible outcomes =92

Here

Number of pages whose sum of its page is 9=10

i.e. 9,18,27,36,45,54,63,72,81,90

Question 14.

Two coins are tossed together. What is the probability of getting:

(ii) both heads or both tails.

Solution:-

A coins has two faces Head and Tail or H.T

Two coins are tossed

Here

Number of coinsÂ =2Ã—2=4Â which are HH, HT, TH, TT

(i) At least one head, then Number of outcomes =3

Question 15.

From 10 identical cards, numbered 1, 2, 3,â€¦, 10, one card is drawn at random. Find the probability that the number on the card drawn is a multiple of:

(i) 2

(ii) 3

(iii) 2 and 3

(iv) 2 or 3

Solution:-

Total outcomes =10

i.e. 1, 2, 3, 4, 5, 6, 7, 8, 9, 10

(i) Favorable outcomes =5 i.e. 2, 4, 6, 8, 10