BTGmoderatorDC wrote:Is the average age of a class of 60 students more than 30 years?
(1) 59 students in the class are exactly 30 years of age each.
(2) The average age of 5 of the students in the class is less than 30 years.
If the average age of the students is exactly 30, then the sum of the 60 ages = 60*30 = 1800.
Implication:
For the average age to be GREATER THAN 30, the SUM of the 60 ages must be GREATER THAN 1800.
Question stem, rephrased:
Is the sum of the 60 ages greater than 1800?
Statement 1:
Since the age of the 60th student is unknown, it is not possible to determine whether the sum of the 60 ages is greater than 1800.
INSUFFICIENT.
Statement 2:
Implication:
Among these 5 students, at least one must be less than 30 years of age.
Since the ages of the other 55 students are unknown, it is not possible to determine whether the sum of the 60 ages is greater than 1800.
INSUFFICIENT.
Statements combined:
Since 59 students are exactly 30 years of age, and at least one of the 60 students must be less than 30 years of age, we get:
Sum of the 60 ages = (59*60) + (integer less than 30) = sum less than 1800.
Thus, the answer to the question stem is NO.
SUFFICIENT.
The correct answer is
C.
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