For number 1)
you must first split the figure, so subtract the 8 mm from 12 mm to find the width.... = 4mm
so you use the numbers 10 x 2 x 4 = 80 mm
and 2 x 8 x 3 = 48 mm
80 mm + 48 mm = volume of the figure
Adults and children of all ages! In order to find the most accurate results, you need a larger sample space :)