1. If y varies inversely as x and x=3 when y=2. find y when x=15

Solution:
`y prop 1/x`

`=>y=k*1/x`

Now, `x=3" when "y=2`

`=>2=k*1/3`

`=>k=2*3`

`=>k=6`

Hence, `y=6*1/x`

we have to find `y" when "x=15`

`=>y=6*1/15`

`=>y=2/5`

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2. y prop 1/x and x=2 when y=2. find y when x=3

Solution:
`y prop 1/x`

`=>y=k*1/x`

Now, `x=2" when "y=2`

`=>2=k*1/2`

`=>k=2*2`

`=>k=4`

Hence, `y=4*1/x`

we have to find `y" when "x=3`

`=>y=4*1/3`

`=>y=4/3`

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3. y prop 1/x^3 and x=2 when y=1/2. find y when x=3

Solution:
`y prop 1/x^3`

`=>y=k*1/x^3`

Now, `x=2" when "y=1/2`

`=>1/2=k*1/2^3`

`=>1/2=k*1/8`

`=>k=1/2*8`

`=>k=4`

Hence, `y=4*1/x^3`

we have to find `y" when "x=3`

`=>y=4*1/3^3`

`=>y=4*1/27`

`=>y=4/27`

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