Brunidad D.
asked 08/11/15Over a period of a week, the 4 people in Group C ran a total of 27 miles, while the 6 people in Group D ran a total of 39 miles. On average, who ran more miles
3 Answers By Expert Tutors

David W. answered 08/11/15
Experienced Prof
If you read the question very carefully, it asks you to compare the average number of miles per day for individuals in Group C versus individuals in Group D.
It does not ask for individual numbers; it asks us to compare group averages. On average, Group C ran (27 miles / 4 people) and, on average, Group D ran (39 miles / 6 people). That is simply comparing 27/4 to 39/6, right? So, which is more miles per person?
Well, most people look at that and don't immediately know which is larger. That's why a common denominator or a representation as a decimal is very helpful. (note: I taught fractions to a very experienced mechanic who could tell immediately whether 2/3 was bigger than 5/8, but I told him that the typical student needed the math solution).
So, keeping everything in ratios (fractions) and using 12 as a common denominator, we are comparing:
27/4 ?? 39/6
81/12 ?? 78/12
81/12 > 78/12 (is this two steps, or what? !!)
On average, individuals in Group C ran more miles per day than individuals in Group D.
Now, if you want to calculate specific averages, or use decimals or cross-multiply fractions or other operations, go ahead and spend the extra time.

Claudine J. answered 08/11/15
10 Years of Teaching & Standardized Testing Experience
Cassandra L. answered 08/11/15
Cassandra-Math Tutor serving Queens
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Nick P.
08/11/15