6. The time () required to travel a given fixed distance
is inversely proportion to the speed (r).
7. The interest (I) of a loan varies jointly as the
principal (P), rate (r) and time (t) the loan was taken
8. The area (A) of a parallelogram varies jointly as the
base (b) and the altitude (h).
9. G varies directly as Q and inversely as L.
10. The electrical resistance (R) varies directly as the
length (L) of wire and inversely as the square of the
diameter (d)​