Chapter 12, Problem 66RE

To determine

To find: The number of tiles required.

Answer to Problem 66RE

The number of tiles required is $360$ .

Explanation of Solution

The number of tiles required is calculated as,

  $\begin{array}{c}\text{Number}\text{of}\text{tiles}=15+16+17+\mathrm{...}+30\\ =\left(1+2+3+\mathrm{...}+30\right)+\left(1+2+3+\mathrm{...}+14\right)\\ =\frac{30\left(30+1\right)}{2}-\frac{14\left(14+1\right)}{2}\\ =360\end{array}$

Therefore, The number of tiles required is $360$ .