How many bags of concrete do I need to fill a hole and what consistency?

I am digging 2 clothes line poles 2 1/2 feet deep and 2 feet wide.. The hole is deep because I dont want the poles to fall over after all this work. I plan to mix it in a wheel barrel and scoop it in with a shovel and am not sure how thick to make the concrete.
1. cake mix thick
2. cookie dough thick
3. drop bisquit thick
Any suggestions to make this easier will be appreciated.

that a big frickin hole.you dont need one that big around.id go about 12".i did some and just poured the mix in dry and tamped it real good.let your garden hose trickle water very slowly so that it absorbs it at the same rate.after it wont absorb anymore let it set a few days before putting the lines on.2-40lb bags should be plenty.mine were still standing after 25+ yrs.had to use a tractor to pull them up

I have found that the consistance of mashed potatoes works well. I would say one bag per hole should be sufficient. I always put some rocks in the hole before pouring in the concrete also.

Easier to do it like fence posts. Set the posts plumb and pour the dry mix (Quik-crete) into the hole and cover with water. Probably take an 80 pound bag each for that size hole..

Your holes to big and not deep enough. Go 4' deep and 10"-12" around. Use sono tube and 4 bags of "post set mix" .put your sono tube in the hole back fill and tamp around the sonotube. put 4" of 3/4 gravel at the bottom,insert and support the pole, fill the tube with water and add the post mix evenly. Check that the post is verticle before completely filling the tube . top off the tube with mix , it should not be dry on top. if it is add water. This stuff will set in about 45 min and dries in 24-36 hrs. no mixing required. fil hole with water and add concrete mix. walk away. Just make sure post is straight before walking away

Mix with a hoe until cake mix like. If there is water standing on the surface, you've added too much water.

Although, in this application, it really doesn't matter.