EXERCISE 3.5

If $s$ varies directly as $u^{2}$ and inversely as $v$ and $s = 7$ when $u = 3$ , $v = 2$ . Find the value of $s$ when $u = 6$ and $v = 10$ .

If $w$ varies jointly as $x$ , $y^{2}$ and $z$ and $w = 5$ when $x = 2$ , $y = 3$ , $z = 10$ . Find $w$ when $x = 4$ , $y = 7$ and $z = 3$ .

If $y$ varies directly as $x^{3}$ and inversely as $z^{2}$ and $t$ , and $y = 16$ when $x = 4$ , $z = 2$ , $t = 3$ . Find the value of $y$ when $x = 2$ , $z = 3$ and $t = 4$ .