How much water should be filled in a container of height `21 cm,` so that it appears half filled to the observer when viewed from the top of the container `(mu=4//3).`

How much water (in cm) should be filled in a container of height 12 cm, so that it appears half filled to the observer when viewed from the top of the container (mu=4//3) .

How much height of water in cm would be filled in a container of height 14 cm,so that it appears half filled to the observer when viewed from the top of the container (mu_(omega)=4/3)

How much water should be filled in a container 21 cm in height, so that it appaers half filled when viewed from the top of the contaier? [Given that : _(a) mu _(w) = (4)/(3) ]