Wondering if there is a way to use an array formula for this?

I'm trying to multiply data for several months (data arranged in columns) by
values contained in one column. In the example below I want to multiply .5
by 100, 125 and 75, .7 by 100, 125 and 75, etc. Then take the sum of these
products. I was thinking {sum(b1:d6*a2:a6)} would work, but it returns an
error.

Multiplier Jan Feb Mar
0.5 100 125 75
0.7 100 125 75
0.9 100 125 75
0.4 100 125 75
0.3 100 125 75


Any help on this is greatly appreciated.

Thanks