S1 as level cie stat help

Why can’t I answer b ii using binomials
Attached images below , answer is 0.939
My workings too

You can't use the binomial distribution because it's only applicable to cases of independent trials, and here they're not independent, because once you've selected one biscuit, you can't select that same biscuit again. (In other words, you have a "sampling without replacement" situation). Thus you need to use a combinatorial method instead.

You can't use the binomial distribution because it's only applicable to cases of independent trials, and here they're not independent, because once you've selected one biscuit, you can't select that same biscuit again. (In other words, you have a "sampling without replacement" situation). Thus you need to use a combinatorial method instead.

Can you please tell me how you would approach this question , without using the subtraction method
There are 4 A books
5 C books and 2 B books each time of book has books that are identical