12th Standard cbse -- Maths - Probability

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Question - 1

Let A and B be two given events such that P(A) = 0.6, P(B) = 0.2 and P(A/B) = 0.5. Then P(A’/B’) is

  • A \(\frac { 1 }{ 10 } \)
  • B \(\frac { 3 }{ 10 } \)
  • C \(\frac { 3 }{ 8 } \)
  • D \(\frac { 3 }{ 8 } \)

Question - 2

Let A and B be two given independent events such that P(A) =p and P(B) = q and P(exactly one of A, B) = \(\frac23\), then value of 3p + 3q – 6pq is

  • A 2
  • B -2
  • C 4
  • D -4

Question - 3

If P(A ∩ B) = 70% and P(B) = 85%, then P(A/B) is equal to

  • A \(\frac{14}{17}\)
  • B \(\frac{17}{20}\)
  • C \(\frac78\)
  • D \(\frac18\)

Question - 4

Two dice are thrown once. If it is known that the sum of the numbers on the dice was less than 6 the probability of getting a sum 3 is

  • A \(\frac{1}{18}\)
  • B \(\frac{5}{18}\)
  • C \(\frac15\)
  • D \(\frac25\)

Question - 5

Three balls are drawn from a bag containing 2 red and 5 black balls, if the random variable X represents the number of red balls drawn, then X can take values

  • A 0, 1, 2
  • B 0, 1, 2, 3
  • C 0
  • D 1, 2

Question - 6

The probability distribution of the discrete variable X is given as:

X 2 3 4 5
P(X) \(\frac{5}{k}\) \(\frac{7}{k}\) \(\frac{9}{5}\) \(\frac{11}{k}\)

The value of k is

  • A 8
  • B 16
  • C 32
  • D 48

Question - 7

If P(A) = \(\frac12\), P(B) = 0, then P(A|B) is

  • A 0
  • B \(\frac12\)
  • C not defined
  • D 1

Question - 8

If A and B are events such that P(A|B) = P(B|A), then

  • A A ⊂ B but A ≠ B
  • B A = B
  • C A ∩ B = Φ
  • D P(A) = P(B)

Question - 9

The probability of obtaining an even prime number on each die, when a pair of dice is rolled is

  • A 0
  • B \(\frac13\)
  • C \(\frac{1}{12}\)
  • D \(\frac{1}{36}\)

Question - 10

Probability that A speaks truth is \(\frac45\). A coin is tossed. A reports that a head appears. The probability that actually there was head is

  • A \(\frac45\)
  • B \(\frac12\)
  • C \(\frac15\)
  • D \(\frac25\)
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