Ex 15.1 Q18
Question A box contains 90 discs which are numbered from 1 to 90. If one disc is drawn at random from the box, find the probability that it bears
(i) a two digit number.
(ii) a perfect square number.
(iii) a number divisible by 5.
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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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