<p>5 letters are selected at random from the 9 letters in the word CELESTIAL. Find the number of different selections if the 5 letters include at least one E and at most one L.</p><p style="text-align: right;">[3]</p>

5 letters are selected at random from the 9 letters in the word CELESTIAL. Find the number of different selections if the 5 letters include at least one E and at most one L.

Permutation and Combination - General

Permutation and Combination

International Baccalaureate Higher Level Mathematics

IB HL Math

Permutations and Combinations Q4: Letters Selected at Random

Letters: 1C, 2Es, 2Ls, 1S, 1T, 1I, 1A = 9 letters

6 others (non-repeated): C, S, T, I, A + 1 more

Case I: (E, W, X, Y, Z) - 1E with 4 different letters from others

Case II: (E, E, X, Y, Z) - 2Es with 3 different letters

Permutations and Combinations Q4: Letters Selected at Random

Permutations and Combinations Q4: Letters Selected at Random

Video Solution: