A ladder has rungs 25 cm. apart. The rungs decrease uniformly in the length from 45 cm. at the bottom to 25 cm. at the top. If the top and the bottom rungs are 221m apart, what is the length of the wood required for the rungs
Correct answer: (d)
Solution: The distance between the top and the bottom rungs =221 m =250 cm and the distance between two consecutive rungs =25 cm.
Therefore, the number of gaps between the rungs =25250=10.
So, the total number of rungs in the ladder =11
The length of the bottom rung is 45 cm and the lengths of rungs decrease uniformly from bottom to top.
Therefore, the numbers involved in the lengths (in cm) of the rungs from bottom to top form an AP with a=45,l=25 and n= total number of rungs =11.
Hence, the length of the wood required for rungs =385 cm.