Bunuel wrote:
A decorator bought a bolt of defective cloth that he judged to be 3/4 usable, in which case the cost would be $0.80 per usable yard. If it was later found that only 2/3 of the bolt could be used, what was the actual cost per usable yard?
A. $0.60
B. $0.90
C. $1.00
D. $1.20
E. $1.70
Let total amount of fabric = T
Hence total useable amount he judged = ¾ T
$0.8/Useable yard x Total Useable amount = Total paid by decorator = $0.6 T
He later found out that only ⅔ T was actually useable and he already paid $0.6T, so what changes here to maintain the total he already pad ($0.6T) is the amount paid per useable yard.
Let actual cost per useable yard = y
Hence actual total useable amount = ⅔ T
$y/Useable yard x Total Useable Amount = $0.6 T ----> y * ⅔ T = 0.6 T -----> y = $0.9/Useable yard