mathsArithmetic progression
posted by Anonymous on .
A ladder has rungs 25 cm apart.The rungs decrease uniformly in length from 45 cm at the bottom to 25 cm at the top.If the top and the botom rungs are two nd a half metre apart, what is the length of the wood required for the rungs

The number of rungs is eleven. Measured from the bottom rung up, their vertical distances are 0, 0.25, 0.50, 0.75, 1.0. 1.25, 1.50, 1.75, 2.00, 2.25 and 2.50 meters. Rung length increases from 45 at the bottom to 25 at the top, so rung lengths are:
45, 43, 41, 39, 37, 35, 33, 31, 29, 27 and 25 cm.
Add up those numbers for wood length required. Looks like 11 x 35 = 385 cm