Solve $80\cdot 0.4+90\cdot 0.6$

Step-by-step solution

1. Step 1 · Check weights
   $$0.4+0.6=1$$

   The weights represent the whole, so their sum is 1.

2. Step 2 · Weighted mean
   $$80(0.4)+90(0.6)=32+54=86$$

   Multiply each value by its share. The result is between 80 and 90 and closer to the more heavily weighted 90.