- Lamar's rate of work = l.
- Mauricio's rate of work = m.
- Together, say they worked for time "t".
Work done = (l+m) * t
To do this work alone, what time would Lamar take?Time taken by Lamar alone = Work/Rate = \(\frac{(l+m) * t }{ l}\)
To do this work alone, what time would Mauricio take? Time taken by Mauricio alone = Work/Rate = \(\frac{(l+m) * t }{ m}\)
(1) Lamar saved 5 min by working with Mauricio\(\frac{(l+m) * t }{ l}\) - 5 = t
\(\frac{(l+m) * t }{ l}\) - t = 5
(t) (\(\frac{(l+m)}{l}\) - 1) = 5
(t) (\(\frac{m}{l}\)) = 5
t = 5 (\(\frac{l}{m}\))
(2) Mauricio saved 45 min by working with Lamar\(\frac{(l+m) * t }{ m}\) - 45 = t
\(\frac{(l+m) * t }{ m}\) - t = 45
(t) (\(\frac{(l+m)}{m}\) - 1) = 45
(t) (\(\frac{l}{m}\)) = 45
t = 45 (\(\frac{m}{l}\))
From (1) and (2)t = 5 (\(\frac{l}{m}\)) = 45 (\(\frac{m}{l}\))
This boils down to ->
\(l^2\) = 9\(m^2\)
l = 3m.This is all we need to solve the question.
Fraction of the work done by Mauricio = \(\frac{Mauricio's work }{ Total Work}\) = \(\frac{m(t)}{(l+m)(t)}\)
= \(\frac{m}{(l+m)}\) = \(\frac{m}{(m+3m)}\) = \(\frac{m}{4m}\) = \(\frac{1}{4}\).
Choice D.