Class 10 Complementary Events — practice questions with answers

Statistics · 5 sample questions from the school syllabus. Try each one, then open the answer and the worked solution.

1. If P(E) = 0.7, what is P(not E)?

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Answer: A) 0.3

P(not E) = 1 - P(E) = 1 - 0.7 = 0.3.

2. The probability that Arjun passes a test is 0.92. Find the probability that he fails.

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Answer: D) 0.08

P(fail) = 1 - 0.92 = 0.08.

3. The probability of an impossible event is 0. Its complement (a sure event) has probability:

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Answer: C) 1

P(sure event) = 1 - P(impossible event) = 1 - 0 = 1.

4. In a deck of 52 cards, a card is drawn at random.
The probability that the card is a face card (J, Q, K) is

\frac{12}{52}

.
What is the probability that the card is NOT a face card?

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Answer: A)

\frac{40}{52}

There are 12 face cards. P(not face) = 1 -

\frac{12}{52}

\frac{40}{52}

5. A bag contains green, red and yellow balls.
P(green) =

\frac{1}{4}

and P(red) =

\frac{1}{3}

.
Using the idea that the three probabilities add to 1, find P(yellow), which is the complement of (green or red).

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Answer: A)

\frac{5}{12}

P(green or red) =

\frac{1}{4} + \frac{1}{3} = \frac{3}{12} + \frac{4}{12} = \frac{7}{12}

. P(yellow) = 1 -

\frac{7}{12}

\frac{5}{12}

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