CAT Quantitative Ability Questions | CAT Permutation, Combination and Probability questions

Comprehension

Directions for questions: Read the information given below and answer the questions that follow :

A string of three English letters is formed as per the following rules :

(a) The first letter is any vowel.

(b) The second letter is m, n or p

(c) If the second letter is m then the third letter is any vowel which is different from the first letter

(d) If the second letter is n then the third letter is e or u.

(e) If second letter is p then the third letter is the same as the first letter

CAT/2003

Question . 31

How many strings of letters can possibly be formed using the above rules?

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Explanatory Answer

Method of solving this CAT Quantitative Ability Question from Permutation, Combination and Probability question

(d) 5 vowels = a, e, i, o and uIf second letter is m then no. of strings = 5 × 4 = 20

If second letter is n then no. of strings = 5 × 2 = 10

If second letter is P then no. of strings = 5 × 1 = 5

Total string of letters can be formed = 20 + 10 + 5 = 35