<p>I need help with this combination problem. So there are 5 math books, 4 physics books and 3 bio books. What are all the different combinations in groups of three books. Ok...so this is how I went about it:
the books can be:
MMM MMF MMB MFB
FFF FFM FFB FMB
BBB BBF BBM BMF</p>
<p>So in total their are really only 10 different ways I can choose the books ( becuase MFB=FMB=BMF). Now on to the combinations within those groups:</p>
<p>MMM= (5C3); MMF= (5C2)(4C1), MMB= (5C2)(3C1)
FFF= (4C3), FFM=(4C2)(5C1), FFB= (4C2)(3C1)
BBB=(3C3), BBM=(3C2)(5C1), BBF=(3C2)(4C1), and MFB=(5C1)(4C1)(3C1)</p>
<p>so the total number of combinations would be=
MMM+MMF+MMB+FFF+FFM+FFB+BBB+BBF+BBM+MFB=</p>
<p>I'm not gonna plug in the numbers becuase I only need to know if my process sounds logical. So is this a safe way to approach this problem or am I doing it wrong? thanks</p>