Section B ( 52 marks )
10 . A cylinder with an open end , with height h cm and radius r cm , has volume
3
V cm . It is given that the sum of the diameter and the height of the cylinder is 20 cm .
( a ) Express r in terms of h .
( b ) Hence , express V in terms of h .
The costs of the painting materials for the curved surface and the base are
2 $ 3 / cm and materials needed .
( c ) Show that
2
$ 4 / cm respectively . Let $ Q be the total cost of the painting
Q h h
2
� 2 �( 200 �10 � ) .
It is also given that there is a maximum value for Q .
[ 2 ]
[ 2 ]
[ 4 ]
( d ) Find the maximum value of Q . [ 7 ]
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