Bunuel wrote:
Geoff is setting up an aquarium and must choose 4 of 6 different fish and 2 of 3 different plants. How many different combinations of fish and plants can Geoff choose?
A. 8
B. 12
C. 18
D. 45
E. 90
this is an AND question
4 fish selected out of 6, (sequence of selection doesn't matter ), total combinations =\(\frac{6!}{4!*2!}\)
2 plants selected out of 3, (sequence of selection doesn't matter ), total combinations =\(\frac{3!}{1!*2!}\)
=\(\frac{6!}{4!*2!}\) * \(\frac{3!}{1!*2!}\) = 45
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