M05-30

It is one of the gmatclub test questions which I always get wrong. Thanks Bunuel for the beautiful explanation.

I think this is a high-quality question and I agree with explanation.

I think this is a high-quality question and I agree with explanation.

I have edited the question and the solution by adding more details to enhance its clarity. I hope it is now easier to understand.

I also think this is a high-quality question.

I think this is a high-quality question and I agree with explanation.

(+) Solution:
Concept Note
Median is a measure of central tendency of a data set such that it represents a point where half of the data lies before and after it. It is the middle most observation within a dataset.
Median Calculation for ungrouped data: (ungrouped data: there are absolute numbers only, no frequencies wrt some data classes)
(1) Arrange the data in ascending order.
(2) Count the total number of observations, denoted as “n”.
(3) - If n is odd, the median is the middle value:
Median = [ (n + 1) / 2 ] term
    - If n is even, the median is the average of the two middle values:
Median = [ (n/2) ] term + [ (n/2 + 1) ] term divided by 2

Approaching the Question
Given:
flights arrived every hour for 24 hours on a certain Saturday
i.e. every hour (24 counts) we have some flights coming in (crazy concert lineup me thinks)
Need to find out:
total number of flights > 180

Method:
Statement 1: If we know that the median is 17,
then lets go with the worst case scenario (least possible values)
that, from the middle to the top we only have 17 in the record & every value beneath the middle point (median) is measly 1,2 etc.
then,
(least value)>>>> middle value: 17.....> max value
since we know the total count is 24, then according to the concept note of median,
(N/2 or 24/2 or) for 12 hours the number of flights should be higher or equal to 17.

going back to being a menace means considering 17 flights each must have landed for at least 11 hours straight.
this is still 187 flights in number (already!)
(ignoring 12 values before median that could be lower compared to 17, and max value that could be 17 or higher: we still, already have 187 flights within 11 hours)
thus, Statement 1 is sufficient as is.

Statement 2: Max flight is 30 counts per hour
> this will hint at the least number of flights for an hour IF we know another central tendency as well. Since we already have the 187>180 revelation with statement 1, this statement is not really required.
+ we will need to focus on knowing the central tendency of the data set to understand how all the observations lined up.­

TLDR: Knowing the central tendency: median case, we can already take up 17*11=187 (min possible values associated for other top half) calcultation to understand the #of flights that linedup for this certain Saturday. Thus statement 1 then, is sufficient as is.
Statement 2 not being central tendency, can be kicked out bro.­