1.It is given that V varies jointly as r 2次 and h
SUB V=108 r=3 and h=4
a) Find an equation connecting h,r,V.
b) If r is halved and h is doubled, find the ratio of the new value of V to its
orginal value.
我識計a,但唔識b
2.The time (x min) required to boil a kettle of water varies directly as the
volume(V cm3)of water and inversely as the power(P W) of the stove.
It is given that the volumes of two kettles of water re in the ratio 9:13
and the power of the stove used to boil them respectively are in the ratio
12:13.If 9 minutes is required to boil the first kettle of water,find the time
required to boil the second kettle.