38. Exercise problem XXXIII

A ladder has rungs $25 cm$ apart. (see Figure). The rungs decrease uniformly in length from $45 cm$ at the bottom to $25 cm$ at the top. If the top and the bottom rungs are $2\frac{1}{2} m$ apart, what is the length of the wood required for the rungs?

 

 

The length of the wood required for the rungs is $cm$.