A cistern of capacity 8000 litres measures externally 3.3 m by 2.6 m by 1.6 m and its walls are 5 cm thick. The thickness of the bottom is:
Pick one:
A) 90 cm
B) 6 dm
C) 1 m
D) 1.1 cm
E) None of these
Explanation:   Let the thickness of the bottom be x cm.   Then , [(330 - 10) × (260 - 10) × (160 - x)] = 8000 × 1000   =&gt; 320 × 250 × (160 - x) = 8000 × 1000   =&gt; (160 - x) = 8000×1000/320=   100   =&gt; x = 60 cm = 6 dm.   Answer: 6 dm
<result>B</result>
A cistern of capacity 8000 litres measures externally 3.3 m by 2.6 m by 1.6 m and its walls are 5 cm thick. The thickness of the bottom is: