A painter has painted one-third of a rectangular wall which is ten feet high. When he will paint another 75 square feet of that wall, he will have finished three-quarters of the job. What is the length (the horizontal dimension) of the wall?
a 18 feet
b 12 feet
c 10 feet
d 9 feet
Answers
Step-by-step explanation:
An additional approach to the one given above, which is especially useful if we tend to be confused by word problems, is to just use the answers.
This is an Alternative method.
Let's say the answer is the median - (C).
If the length is 10 feet then the dimensions are 10 by 10 and the area is 100 square feet.
So 1/3 of 100 = 33 square feet have been painted and there are only 67 left.
This is impossible as we know that an additional 75 square feet can be painted.
We need a larger length so (C) is eliminated, along with the smaller (D) and (E).
Repeating for (B) gives a total area of 120 meaning that 40 have been painted.
If another 75 were painted then a total of 40 + 75 = 115 would be painted, more than 3/4.
(B) is eliminated.
(A) is our answer.