posted by Bella bell .
How many line segments can be drawn between each 15 points? No three points are in straight line.
Which five consecutive numbers equals 175?
Farmer has ducks and cows in his farm. If all together t animals have 60 heads and 70 feet how many ducks and how many cows does farmer has?
<<Which five consecutive numbers equals 175?>>
The average is 175/5 = 35, and that must be the "middle" number.
Since they are consecutive integers, they are 33, 34, 35, 36 and 37
You must have copied the last question incorrectly, unless there are a lot on one-legged cows and ducks
Consider one of the points. If there are n points, you can draw n-1 lines from that point to the others.
By the time you have drawn all lines from n points, you have drawn n(n-1) lines. But each line is drawn twice. The line from point 6 to point 3 is the same line as was already drawn from point 3 to point 6.
There are thus n(n-1)/2 lines.
For this problem, n=15.