In a 12" x 17" pan? Don't do it, that will overflow. You can barely bake two boxes per sheet, it's nearly too much. As for the timing for two boxes, it's about 35-45 minutes at 325-350 degrees.
Poke some holes in it with a fork and wrap in foil bake at 300 degrees for 1 to 1 1/2 hours.In the microwave no foil and cook on high for 8 to 10 minutes.
A half sheet cake typically weighs between 6 to 8 pounds, depending on the ingredients and the density of the cake. The dimensions of a half sheet cake are usually about 13 by 18 inches, and the weight can vary based on the type of cake and frosting used. If filled with heavy ingredients or layered, it may weigh more.
Well. If you made the half cake from a box then do and estimate for about half the time for a whole cake. I LOVE baking.
The boxes I checked said one box would make a 13x9, so you will need about 1 1/2 boxes for a 12x18. Assuming the pan is deep enough you could use two boxes for a one layer 12x18 or you may want to make a two layer cake using 1 1/2 box per layer.
Figure on a half-sheet pan; around 18" by 13". Or you could use two quarter-sheet pans (9x13) and combine them; this may work better in a home oven. Quarter-sheets are convenient, because they're the "standard size" for home pans, and they're the size pan that boxes of cake mix are designed for.
You can bake two batches of cookies at the same time if you have enough cookie sheets and oven space. If you do not have enough space, you can bake half of them, and then bake the second half immediately after.
It will probably take 1-1/2 boxes. Fill the pan roughly half full & use the rest for cupcakes.
Okay so here you go! There are approximately 4-5 cups of batter in one cake mix. For a half of a sheet cake, I use 3 cake mixes, so for a full, that's 6. You will have a little bit left over too.
1 cake
It varies greatly. Some are small, some are larger. Typically, most are about 9 inches by 13 inches, and 2 inches deep. Any variation within 2 or 3 inches of this is considered about "average".
Physical changes are ones which do not affect the chemical composition of a substance. For instance, if you cut a cake in half, that is a physical change. Nothing has changed except the shape, weight, and size of the cake. When you bake the cake batter, however, you are causing a chemical change. The batter changes into a cake; when you cut the cake, it doesn't change into anything.
If Jackie has 1/3 of half a cake then he had half of half a cake. This is a math problem.