Question 157563
You need to know how many times can you get 2.5 cu.yds. out of 10 cu. yds. or out of 12 cu.yds.
Divide 10 by 2.5
{{{10/2.5 = 4}}} and 
{{{12/2.5 = 4.8}}}
So it wil take between 4 and 4.8 hours to pour the slab. That's between 4 hours and 4 hours, 48 minutes.