## fatboy12 Group Title Find the probability of randomly selecting three science books and four history books from a box containing five science books and six history books. one year ago one year ago

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1. hba Group Title

5C3+6C4=

2. wio Group Title

@hba Why would we be adding in this case? It's not "three science books OR four history books"

3. hba Group Title

4. wio Group Title

No problem, I wasn't even sure that you were wrong, I was just confused.

5. wio Group Title

My guess is $$\binom{5}{3} \times \binom{6}{4} \div \binom{11}{7}$$ It's assuming they meant to say "choosing 7 books randomly". Because otherwise it could be 100% or even 0%.

6. hartnn Group Title

^ thats correct.

7. hba Group Title

The answer would be 5/11 then ?

8. wio Group Title

If I am correct then wolfram agrees: http://www.wolframalpha.com/input/?i=%285+choose+3%29+*+%286+choose+4%29++%2F+%2811+choose+7%29

9. hba Group Title