SOLUTION: revenue for the first 4 days + revenue for the last 6 days = total
revenue
Total revenue = A × N = $40,000 × 10 = $400,000
Revenue for the first four days = A × N = $25,000 × 4 = $100,000
Revenue for the last 6 days = A × 6 = 6A, where A is the average daily revenue
for the last 6 days.
Thus:
$100,000 + 6A = $400,000
6 A = $300,000
A = $300,000 6 = $50,000Weighted Averages
When determining the average of two data points, the average will always fall
in the middle of the two data points. For example, the average of 30 and 40 =
30 + 40
2 =70
2 = 35.30 4035But what if one of the data points appears more often than the other data point?
For example: What is the average of 30, 30, and 40? In this case, the average =
30 + 30 + 40
3 =100
3 = 33.33. Now that you have added an additional data point of 30 to
the set, the average is weighted closer to 30 than it is to 40.30 4033.33The preceding example represents a weighted average. You will have a weighted
average any time the frequency of a data point pulls the average closer to that data
point than to the other data point. In the preceding example, the fact that there
were more 30s than 40s meant that the average was skewed more toward 30 than
toward 40.Quantitative Comparison Strategy
Weighted averages are tested most frequently in Quantitative
Comparison questions. For these questions, it is important to keep in
mind the mandate that you must minimize calculations! Oftentimes,
one of the quantities will be the average of the set if the number of data
points were equal. Think about which data point the average is skewed
toward, and you will cut back on time spent calculating.
A student took 10 exams for his biology course. His average on 6 of the
exams was 80. His average on the other 4 exams was 90.
Quantity A Quantity B
His average for the course 85CHAPTER 12 ■ FROM WORDS TO ALGEBRA 32904-GRE-Test-2018_313-462.indd 329 12/05/17 12:03 pm