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In How Many Ways Can a Student Choose a Programme of 5 Courses If 9 Courses Are Available and 2 Specific Courses Are Compulsory for Every Student?

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Question

In how many ways can a student choose a programme of 5 courses if 9 courses are available and 2 specific courses are compulsory for every student?

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Solution

2 courses are compulsory out of the 9 available courses. There are 7 more courses.
So, we need to choose 3 courses out of 7 courses.
∴ Required number of ways =\[{}^7 C_3 = \frac{7}{3} \times \frac{6}{2} \times \frac{5}{1} = 35\]

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Chapter 17: Combinations - Exercise 17.2 [Page 17]

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R.D. Sharma Mathematics [English] Class 11
Chapter 17 Combinations
Exercise 17.2 | Q 29 | Page 17

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