While it seems like Mike says 20 instead of 120 at about 0:30 in the explanation, he is referring to the median of 120 at that point. Since 120 is the median of a set with an odd number of values, we know that 120 will be the middle number when we write the values in ascending order. For that reason, if there are n numbers above 120, there must also be n numbers below 120.
Consider {3, 4, 5} median is an even number like the set we have here in this question and the first number is odd. Substitute the values in the answer choice.. A gives the right answer choice.. but instead of 120 in the choice consider 4 as the median..
Hi Deethu. Yes, changing 120 to a different integer doesn't change how the problem works. But 120 shouldn't be difficult to work with either, since we are simply counting consecutive integers after it. 119, 120, 121, for example, are just as easy to work with.
4 Explanations