NCERT Class 11-Math՚S: Exemplar Chapter – 16 Probability Part 5 (For CBSE, ICSE, IAS, NET, NRA 2022)
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Objective Type Questions
Choose the Correct Answer from Given Four Options in Each of the Examples 9 to 15 (M. C. Q.)
Question 9:
In a leap year the probability of having Sundays or Mondays is
(A)
(B)
(C)
(D)
Answer:
(B) Is the correct answer.
Since a leap year has 366 days and hence weeks and days. The days can be .
Therefore,
Question 10:
Three digit numbers are formed using the digits . A number is chosen at random out of these numbers. What is the probability that this number has the same digits?
(A)
(B)
(C)
(D)
Answer:
(D) Is the correct answer. Since a digit number cannot start with digit , the hundredth place can have any of the 4 digits. Now, the tens and units place can have all the digits. Therefore, the total possible 3-digit numbers are , i.e.. , .
The total possible 3 digit numbers having all digits same
Hence,
Question 11:
Three squares of chess board are selected at random. The probability of getting 2 squares of one colour and other of a different colour is
(A)
(B)
(C)
(D)
Answer:
(A) is the correct answer. In a chess board, there are 64 squares of which 32 are white and 32 are black. Since 2 of one colour and 1 of other can be 2W, 1B, or 1W, 2B, the number of ways is and also, the number of ways of choosing any 3 boxes is .
Hence, the required probability
Question 12:
If A and B are any two events having then the probability of is
(A)
(B)
(C)
(D)
Answer:
(C) Is the correct answer.
We have
Question 13:
Three of the six vertices of a regular hexagon are chosen at random. What is the probability that the triangle with these vertices is equilateral?
Answer:
(D) is the correct answer.
ABCDEF is a regular hexagon. Total number of triangles . (Since no three points are collinear) . Of these only ; are equilateral triangles.
Therefore, required probability