1. ## help(urgent)

this is combined variation
if q varies directly as b and inversely as c, and if q=0.2 when b=16 and c=8 find q when b=2 and c=5

and

if t varies directly as s and inversely as v-squared and if t= 0.1 when s=72 and v=6 find s when t=5 and v=0.2

2. pls help i need it tom. I'm just new here i hope u can help me

3. Originally Posted by machilove
this is combined variation
if q varies directly as b and inversely as c, and if q=0.2 when b=16 and c=8 find q when b=2 and c=5
if $q$ varies directly as $b$ then there is a constant $k$ such that:

$q=k\times b$

Now when $q=0.2$, $b=16$, so:

$0.2=k \times 16$,

so:

$k=0.2/16=1/80$,

so when $b=2$ we have:

$q=2/80=1/40$.

if $q$ varies inversely as $c$ then there is a constant $m$ such that:

$q=m/c$

Now when $q=0.2$ $c=8$, so:

$0.2=m/8$,

so:

$m=1.6$.

Hence when $c=5$ $q=1.6/5=8/25$.

RonL