Question 7(c)
[Maximum number: 3]
Two letters are chosen at random from the 10 letters in the word ZOOLOGICAL. Find the probability that these two letters are different.
CAIE A-Level Mathematics 5.3.1 Permutations & combinations
Practise finding probabilities by counting equally likely outcomes with combinations, arrangements and simple enumeration.
How this is tested
- form probability fractions from favourable arrangements over total arrangements
- justify random choice methods by checking that elementary outcomes are equally likely