Question 1064532
<pre>
There are 4 possible line-ups by gender, B=boy, G=girl:

BGBGBG
GBGBGB
BGGBGB
BGBGGB

For each of those 4 line-ups by gender,

The 3 girls can be arranged in 3! or 6 ways
The 3 boys can also be arranged in 3! or 6 ways.

That's (4)(3!)(3!) = (4)(6)(6) = 144 ways.

Edwin</pre>