CBSE Class 10 Mathematics
Question 21 of 29
Probability — Question Ex 15.1 Q21
Back to all questions Ex 15.1 Q21
Question A lot consists of 144 ball pens of which 20 are defective and the others are good. Nuri will buy a pen if it is good, but will not buy if it is defective. The shopkeeper draws one pen at random and gives it to her. What is the probability that
(i) she will buy it?
(ii) she will not buy it?
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CBSE Class 10 Probability — Complete Guide
Probability is an easy-to-score chapter worth 4-5 marks. Classical probability with coins, dice, cards, and bags.
Quick Revision: Key Concepts
- P(E) = favourable / total outcomes
- Complementary: P(E) + P(not E) = 1
- Range: 0 ≤ P(E) ≤ 1
- Cards: 52 total, 4 suits, 12 face cards, 26 red, 26 black
Most Important Questions
- Coin and dice probability problems
- Playing card probability (specific suit, face card, etc.)
- Balls in a bag problems
- Number/divisibility probability problems
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