Question

4, 13, 5, 8, R, 5, 11

Answer 1

Answers:

R can be either 8, 9 or 10

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Explanation:

Let's exclude the R value for now.

The set {4,13,5,8,5,11} sorts to {4,5,5,8,11,13}.

Now we'll include R back in. We're told that R is an integer and it's smaller than 11. The possible values R can take on are: {10, 9, 8, 7, ...} The countdown continues forever into the negative territory.

If R < 4, then we go from {4,5,5,8,11,13} to {R,4,5,5,8,11,13}. That R is guaranteed to be the min value since R is less than the smallest value of the previous set. Note that the middle-most item of the second set is 5; however, we want the median to be 8 instead. This allows us to rule out the case that R < 4.

So we've determined that 4 < R < 11. Because R is an integer, we can say it takes on the values from the set {5,6,7,8,9,10}

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If R = 5, then {4,5,5,8,11,13} updates to {4,5,5,5,8,11,13} after adding in that R value. We can see the median is 5, so we can rule out the case that R = 5.

Similarly, we can rule out R = 6 as well. The set {4,5,5,8,11,13} updates to {4,5,5,6,8,11,13} in which the median is 6.

If R = 7, then the median is 7 for similar reasoning and we can rule out this R value.

So we've ruled out the cases that R = 5, R = 6 and R = 7.

If we tried R = 8, then {4,5,5,8,11,13} becomes {4,5,5,R,8,11,13} = {4,5,5,8,8,11,13}. This set has a median of 8 and R = 8 is one of the answers.

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Now let's consider the possibility that 8 < R < 11.

If for instance R = 9, then {4,5,5,8,11,13} becomes {4,5,5,8,9,11,13} to show that this set also has a median of 8. R = 9 is another answer.

The same idea happens when R = 10 as well because we get {4,5,5,8,10,11,13}. R = 10 is another answer.

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In short, R can be any of the following values: 8, 9, 10