Name for a certain statistic


There's a certain statistics that's easy enough to calculate.
But I don't know what it's called.
That is, I'd like to know its name.

The statistics is the point on the x-axis such that
the sum of the y-axis values to the left of the point
is equal to
the sum of y-axis values to the right.

A crude example would be a shop's profit in a 30 day month is
$10/day for day 1 to 10
$20/day for day 11 to 20
$30/day for day 21 to 30.
Total profit is $100 + $200 + $300 = $600.

After day 20 the profit is $100 + $200, which is 1/2 of $600.

So day 20 is the day I'm looking for.

Can anyone tell me what this statistic is called?

Art D'Adamo


Dark Knight
I was giving the statstic name from your example.
Could you tell me
what is x axis variable and y axis variable in your example?
x-axis is day of month.
y-axis is the day's net profit.

So I want the day of the month when
1/2 for the month's profit has been made.