Consider the following 8 numbers, where one labelled x
is unknown.
18, 36, 16, x, 39, 27, 8, 34
Given that the range of the numbers is 56,
work out 2 values of
x
.

Explanation

Consider three scenarios:

These scenarios cover all the possible cases of what x could be. It's either the min, the max, or somewhere in between the min and max.

We'll start with scenario A.

If x is the min, then that must mean 39 is the max as it's the largest of the set {18, 36, 16, 39, 27, 8, 34}

The range is 56, so,

range = max - min

56 = 39 - x

56+x= 39

x = 39-56

x = -17  which is one possible answer

If instead we go with scenario B, then x is the max and 8 is the min

range = max - min

56 = x - 8

56+8 = x

64 = x

x = 64 is the other possible answer

Lastly, let's consider scenario C. If x is not the min or the max, then it's somewhere between the min 8 and max 39. in short, 8 < x < 39.

Note that range = max - min = 39-8 = 31 which is not the range of 56 that we want. So there's no way scenario C can be possible here.

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