There are an infinite number of groups of three that all average 125.
Here are a few:
124, 125, 126
120, 125, 130
100, 125, 150
25, 125, 225
1, 125, 249
3, 73, 299
7, 183, 185
1, 2, 372
.
.
etc.
124, 125 and 126
The average is the sum of the numbers in the set divided by the number of numbers in the set. In this case it is (125+143+134)/3=134.
Well, let's take a moment to appreciate these lovely numbers. To find their average, you simply add them together and then divide by how many numbers you have. So, 125 + 115 + 108 equals 348. And when you divide 348 by 3, you get the average of these beautiful numbers, which is 116.
There can only be 3 of them because as a product of its prime factors: 5*5*5 = 125
They are: .1+.02+.005 = .125
They are: 2*5*11 = 110
Three different numbers that can equal 125 are 50, 40, and 35, since 50 + 40 + 35 = 125. Another example is 60, 30, and 35, which also sums to 125. There are countless combinations, as long as the numbers are distinct and their total is 125.
125
They are: 25+36+64 = 125
1 x 375, 3 x 125, 5 x 75, 15 x 25.
There are 5 numbers which can make the 3 digit numbers in this example. Therefore each digit in the 3 digit number has 5 choices of which number can be placed there. Therefore number of 3 digit numbers = 5 x 5 x 5 = 125
To get the simple average of a series of numbers, you add the numbers up and divide by however many numbers there were. For example, the average of 2, 3 and 4 is the sum of the numbers (which adds up to 9) divided by 3 (because there are three numbers). So the average is 9/3 = 3.