Four letters are selected from the 10 letters of the word SUMMERTIME. Find the number of different selections if the four letters include at least one $$$M$$$ and exactly one $$$E$$$. ........................................................................................................................................................ ........................................................................................................................................................ ........................................................................................................................................................ ........................................................................................................................................................ ........................................................................................................................................................ ........................................................................................................................................................ ........................................................................................................................................................ ........................................................................................................................................................ ........................................................................................................................................................ ........................................................................................................................................................ ........................................................................................................................................................ ........................................................................................................................................................ ........................................................................................................................................................ ........................................................................................................................................................ ........................................................................................................................................................ ........................................................................................................................................................ ........................................................................................................................................................

Mathematics

IGCSE&ALevel

CAIE

Exam No：9709_s20_qp_52 Year：2020 Question No：6(c)

Answer:

Scenarios:
E MMM $\quad{ }^{5} \mathrm{C}_{0}=1$
EMM $\quad{ }^{5} \mathrm{C}_{1}=5$
$\mathrm{EM}_{--} \quad{ }^{5} \mathrm{C}_{2}=10$
Summing the number of ways for 2 or 3 correct scenarios
Total $=16$

Knowledge points:

5.2.1 understand the terms permutation and combination, and solve simple problems involving selections

Answer:

Knowledge points:

Solution:

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