Question

Suppose y varies inversely as x, and y=25 when x=3. Find x when y=15

Answer 1

If

y

varies inversely as

x

then

XXX

x

⋅

y

=

c

for some constant

c

We are told when

x

=

2

then

y

=

15

So

XXX

2

⋅

15

=

c

XXX

⇒

c

=

30

and

XXX

x

⋅

y

=

30

Therefore when

y

=

3

XXX

x

⋅

3

=

30

XXX

→

x

=

10

Explanation: