Current location - Training Enrollment Network - Mathematics courses - Mathematical permutation and combination problem
Mathematical permutation and combination problem
The first step is to classify 1. There is only one colored ball 3 in each bag! There are only two kinds of balls in a bag. A There are white balls and red balls, and there can only be one white ball. Either B is all black balls and C is all red balls, or B is red and C is black. ...

add

Method 2: Use zoning method: white, red, red, black, black, red, red, white, black, black, black, black, black, black, black, black, black, black, black, black, black, black, black, black, black, black, black, black, black.

2

There are 28 kinds of C, so there are 28x6 kinds of A * *.

eight