Alternate rows sumproduct

[spidolster]

Hi,

I got this set of data:
(simplified, in actual could be several hundred rows)

Production A | 10,000
Distance A | 1,200
Production B | 20,000
Distance B | 1,300
Production C | 30,000
Distance C | 1,400
Sum of Production | =row1+row5+row5
distance | =((row1*row2)+(row3*row4)+(row5*row6))/sum of production

My question is:
without modifying data position, what is the most efficient formula to calculate distance?

Thank you.

[samba_ravi]

please attach a sample excel file

[Glenn Kennedy]

Assuning that your data start in A2:

=SUMPRODUCT((MOD(ROW(B2:B7)-ROW(B2),2)=0)+0,B2:B7,B3:B8)/SUMPRODUCT((MOD(ROW(B3:B8)-ROW(B3),2)=0)+0,B3:B8)

[spidolster]

Assuning that your data start in A2:

=SUMPRODUCT((MOD(ROW(B2:B7)-ROW(B2),2)=0)+0,B2:B7,B3:B8)/SUMPRODUCT((MOD(ROW(B3:B8)-ROW(B3),2)=0)+0,B3:B8)

Thanks for your reply, Glenn. But still not solved yet.
Here is the attachment of my problem. I hope this is clear enough.

Edit:
After second thought, maybe my question title is a bit misleading. The solution could be any formula, sumproduct is just the first one that pops in my head when I write this question.

[Phuocam]

Try this ...

=SUMPRODUCT(($A$1:$A$5=A7)*$B$1:$B$5*$B$2:$B$6)/SUMPRODUCT(($A$1:$A$5=A7)*$B$1:$B$5)

[spidolster]

Try this ...

=SUMPRODUCT(($A$1:$A$5=A7)*$B$1:$B$5*$B$2:$B$6)/SUMPRODUCT(($A$1:$A$5=A7)*$B$1:$B$5)

Hey, it works like a charm!
You made it looks so easy. Many thanks!

[Phuocam]

You are welcome.