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chetan2u KarishmaB - any other way to think about this question?
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Russ19
What is the median of the set {a, b, c, d}?

1) The average (arithmetic mean) of a and b is 110.

2) The average (arithmetic mean) of c and d is 110.

We know that each statement is insufficient alone because it tells us nothing about the other two terms.

Together, the simplest case is that each term is 110 i.e. the set is {110, 110, 110, 110}
Median is 110.

When we increase-decrease values in one pair, say we get {100, 110, 110, 120} - one value goes to the left of 110 and the other goes to the right. In the middle, we still have 110s so median is 110.

Now try to change the values in the other pair too. When you reduce one number by a certain amount, you will need to increase the other by the same amount.
So if you make them 109 and 111, they will stay in the middle and still add up to 220
{100, 109, 111, 120}

If you make them 105 and 115, they will stay in the middle and still add up to 220
{100, 105, 115, 120}

If you make them 100 and 120, they will stay in the middle and still add up to 220
{100, 100, 120, 120}

If you make them 90 and 130, they will both move to extremes and the other two numbers will come in the middle and will add up to 220.
{90, 100, 120, 130}

Since the numbers in the pair will always move together, we know that the sum of the middle two numbers will always be 220 and hence the median will always be 110.

Answer (C)

Tip: Start with the simplest case and then introduce one complication at a time.
Check: https://anaprep.com/sets-statistics-mea ... -question/
https://anaprep.com/sets-statistics-imp ... imination/
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What is the median of the set {a, b, c, d}?

1) The average (arithmetic mean) of a and b is 110.

2) The average (arithmetic mean) of c and d is 110.

Here is a 2 min video solution to this tricky problem:

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I have to admit, this is one of the most beautiful questions I have ever seen. It's so easy to mess this one up. If I was at GMAC, I'd definitely take note of this question. Must solve.
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