So for the calculation of material in the slab, first of all, we need to calculate the volume of the slab (V), which is equal to L*B*H= 30*30*0.5= 450cft.

So now we find the dry volume of the slab which is equal to wet volume*1.54, that is 450*1.54= 693 ft ( 1.54 is a constant value )

For the calculation of cement, we use the formula that is the ratio of cement /total ratio*dry volume, which is equal to 1/7*693= 99cft. this is the cement quantity

Now we calculate the aggregate which is equal to the ratio of aggregate /total ratio *dry volume which is equal to 4/7*693= 396cft. this is aggregate quantity.