P varies jointly as m and u and varies inversel... - JAMB Mathematics 2013 Question

P (\propto) mu, p (\propto \frac{1}{q})

p = muk ................ (1)

p = (\frac{1}{q}k).... (2)

Combining (1) and (2), we get

P = (\frac{mu}{q}k)

4 = (\frac{m \times u}{1}k)

giving k = (\frac{4}{6} = \frac{2}{3})

So, P = (\frac{mu}{q} \times \frac{2}{3} = \frac{2mu}{3q})

Hence, P = (\frac{2 \times 6 \times 4}{3 \times \frac{8}{5}})

P = (\frac{2 \times 6 \times 4 \times 5}{3 \times 8})

p = 10