The comparison is now:
Quantity A Quantity B
2 a + 3 b 3 a + 2 5 b
Cross-multiply: ↓
5(2a + b) 3(3a + 2b)
Distribute: ↓
10 a + 5b 9 a + 6b
Subtract 9a from both columns: ↓
a + 5b 6 b
Subtract 5b from both columns: ↓
a b
Since you are told that a > b, Quantity A is greater.
- B To maximize the range, minimize the smallest value and maximize the
greatest value. Since the terms are positive integers, the minimum value for an
item in the set is 1. To maximize the greatest value, minimize the rest of the
terms. In this case, that would mean making them all equal to 1. Therefore:
1 + 1 + 1 + 1 + x = the sum of the set = 100
4 + x = 100
x = 96
The maximum possible range is 96 – 1 = 95. Quantity B is greater. - A The difference between the two sets is the 0 in the second set. Since 0 is
less than the average of 2,19, 34, and 60, the average of the second set must be
smaller than the average of the first set. Quantity A is greater. - B Express Quantity A algebraically:
1
a +
1
b
2
=
b + a
ab
2
= b + a 2 ab
The numerators of the two quantities are the same. Since the denominator of
Quantity B is smaller, that fraction is larger.
- B In Quantity B, each term in Quantity A is doubled. The spread of the set
will thus be doubled. Since the spread in Quantity B is greater, the standard
deviation of Quantity B is greater.
Rates
Rate questions always come in one of two forms: distance or work. In both cases,
there will be a constant relationship between the rate, time, and work or distance:
rate × time = distance
or
rate × time = work
CHAPTER 12 ■ FROM WORDS TO ALGEBRA 339
04-GRE-Test-2018_313-462.indd 339 12/05/17 12:03 pm