Mean and median
Two familiar measures
The mean is the sum of the values divided by how many there are.
Shared by a Veda teacher · Generated with Veda AI · Oct 2026
Veda Bites are swipeable micro-lessons — each one teaches exactly one idea. Here's a taste from this kit; the app has the full deck.
Two familiar measures
The mean is the sum of the values divided by how many there are.
Start with two numbers
Three and 7 average to 5, and 8 and 9 average to 8.5.
The guess that fails
Two numbers make the mean look like the midpoint between the smallest and largest.
What the median answers to
The median is the middle value once the data is sorted, with as many below as above.
Adding a value above it
A set with median 8 gains the value 11, which is above the old median.
Where it lands
The median is then the average of the two middle values.
The mean is not the midpoint between the extremes. It is the one place where the distances below it and the distances above it come to the same total.
~35 min · full explanation, examples & memory tricks in the app
The median answers to counts rather than to distances, so it moves differently from the mean. And a mean can be run backwards to recover a value nobody wrote down.
~40 min · full explanation, examples & memory tricks in the app
A line graph shows how a quantity moves over time. Reading one properly means two separate steps: first setting down what is given, and only then saying what it means.
~35 min · full explanation, examples & memory tricks in the app
105 questions laddered from warm-up to topper-level, each with an explanation. A taste:
The mean of some data is found by adding all its values and then
Beginnerdividing by how many values there are
The median is the middle value once sorted instead.
Taking the two numbers 3 and 7 and then the two numbers 8 and 9, their means come to
Beginner5 and 8.5
Ten over 2, and 17 over 2.
Drawn as dots on a line, the mean of just TWO numbers always sits
Beginnerexactly halfway between them
Which is what makes the next step so tempting.
A pupil concludes from that pair of examples that the mean is always the midpoint between the smallest and largest value, which is
Intermediatewrong as soon as there are three values
Two values is the one case where it happens to hold.
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