Salvaging an Screw Up

Had some issues with the mash on the last batch. I was shooting for an OG of 1.060, but ended up with 1.040. The beer is an American Red.

So I've got 10 gallons at 1.040 and 70 IBUs.

Does it make sense to brew 5 gallons at 1.100 and blend them together after fermentation?

Is my math correct?

10G @ 1.040 + 5G @ 1.100 = 15G @ 1.060


Thanks

Math isright. It's a simple average;

2 parts @40 +
1 part @100 =
3 parts @60

Thanks, mom.

Follow ups:

Should I also go with 70 IBUs on the salvage batch?

Would it be OK to dump it onto the yeast cake from 5G of the original batch?

Yes, go with 70 IBUs and all the flavor and aroma hops you would need for a 5 gallon batch of the original beer.

The ONLY thing you are trying to dilute is the gravity, so you want all other factors to be the same in the 5 gallon batch as the existing 10 gallon batch so that they don't also get diluted when you blend them.

I hope this recipe is a good one.... you're going to have 15 gallons of it to drink.

edit: no opinion about pitching on the cake.