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A student taking a History examination is directed to answer any seven of 10 essay questions. There is no concern about Order here, so the student can answer the examination in how many ways?

1. 110
2. 129
3. 120
4. 140

as order does not matter so we can use combination instead of permutation and

no. of ways to answer is C(10,7)

=120
by
Order doesn't matter, repetitions not allowed. So $_{7}^{10}\textrm{C} = _{3}^{10}\textrm{C} = 120$

1
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