pushpitkc
Bunuel
Eight boxes, weighing an average of 12.75 kilograms, and 12 boxes, weighing an average of 15.25 kilograms, are shipped to the same location. What is the average weight, in kilograms, of the 20 boxes shipped to the location?
(A) 13
(B) 13.25
(C) 14
(D) 14.25
(E) 15
We know 1.25 = \(\frac{5}{4}\). Hence \(\frac{5}{4}*8 = 10\) and \(\frac{5}{4}*12 = 15\)
Average = \(\frac{(14 - 1.25)*8 + (14 + 1.25)*12}{20} = \frac{14*20 - 10 + 15}{20} = 14 + \frac{5}{20} = 14.25\)
Therefore, the average of 20 boxes shipped is
14.25(Option D)P.S In order to solve problems such as these, it is important to identify a pattern to reduce unnecessary calculations.
Great way to simplify this
pushpitkc,
Another way to look at it is -
\(12.75 = 12 \frac{3}{4} improper fraction ... (12*4 +3 )/4 = 51/4\)
\(15.25 = 15 \frac{1}{4} = 61/4\)
Numerator is : \(\frac{51}{4}* 8 + \frac{61}{4}*3 = 50*2 + 60*3 + 2 + 3 = 285\)
On dividing by 20 .. which is 10 * 2
Divide by 2 first and move decimals point one to the left.
Hence \(285 / 2 = 142.5 / 10 = 14.25\)
Hence
Option (D) is correct.
Always try to simplify the calculations as much as possible...
Best,
Gladi