Jaehyun J.

asked • 12/08/20

Permutation and Combination Question

A bookshelf displays different types of books, 6 books in English (E) and 5 books in Spanish (S). If 4 books are chosen among the English language books and 3 are selected from the Spanish language books, calculate how many ways can the 7 books be arranged on a shelf given that

i) There are no restrictions (no concern on the sequence)?

ii) 4 English books must put together?

iii) English and Spanish books must put alternately (i.e. ESESESE).

I am confused. Do I need to apply the combinations method first in order to select the books? or I can just directly solve this problem by using permutation? Please help me solve these questions :(

1 Expert Answer


Jaehyun J.

Thank you so much for your help, sir! I don't quite understand the solution for question 2, why do we have to multiply it with 4? Could you explain?


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