TABLE 2-5
The following are the duration in minutes of a sample of long-distance phone calls made within the continental United States reported by one long-distance carrier.
-Referring to Table 2-5, if 10 calls lasted 30 minutes or more, how many calls lasted less than 5 minutes?
A) 10
B) 185
C) 295
D) 500

Question

TABLE 2-5
The following are the duration in minutes of a sample of long-distance phone calls made within the continental United States reported by one long-distance carrier. 
-Referring to Table 2-5, if 10 calls lasted 30 minutes or more, how many calls lasted less than 5 minutes?
A) 10 
B) 185 
C) 295 
D) 500

Quizplus · Accepted Answer

The table does not provide information about the specific number of phone calls made, only their durations. Therefore, to determine how many calls lasted less than 5 minutes, we need to know the total number of calls in the sample. The only information we have is that there were at least 500 calls in the sample (since this is the largest value in the table).

If 10 calls lasted 30 minutes or more, and there were at least 500 calls in the sample, then the remaining calls in the sample (i.e. those that lasted less than 30 minutes) must be at least 490.

We cannot determine exactly how many of those 490 calls lasted less than 5 minutes, but we do know that it must be less than 490. The only answer choice that reflects this is B (185).

TABLE 2-5 The Following Are the Duration in Minutes of a Sample