



 
Hi Lenton,
1 foot is 12 inches so 5 inches is $\large \frac{5}{12}$ inches. The volume of a slab is the area of the base times the height so your slab of rock has a volume of \[48 \times \frac{5}{12} = 20 \mbox{ cubic feet}\] if it is 5 inches thick. I'll let you do the calculation if it's 3 inches thick. Penny  


Math Central is supported by the University of Regina and the Imperial Oil Foundation. 