## Elementary Technical Mathematics

8$\frac{1}{4}$ hour
Given four tires of a car can be replaced in $\frac{3}{4}$ hour Therefore we need to find how much time it will take to replace tires of 11 cars = 11 $\times$ $\frac{3}{4}$ = $\frac{33}{4}$ =8$\frac{1}{4}$ hour