Problema Solution
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 bottom are 2.5 m apart,what is the length of the wood required for the rungs? [Hint:Find the number(n)of rungs.The distance between the consecutive rungs is constant. This gives d.]
Answer provided by our tutors
the number of rugs n = 250/25 = 10 rugs (since 2.5 m = 250 cm)
the lengths of the rugs decrease uniformly from bottom to top and form Arithmetic Progression with terms:
a1 = 45
a10 = 25
the sum of the first 10 terms of the Arithmetic Progression gives the solution:
S10 = (10/2)(a1 + a10)
S10 = (10/2)(25 + 45)
S10 = 350 cm
The length of the wood required for the rugs is 350 cm.