Priya measured the perimeter of a square desk and found 248 cm. Noah measured the perimeter of the same desk and found 2468 mm. Why do you think Priya and Noah may have found different measurements for the same desk?

Because they used different units of measurement.

Step-by-step explanation:

for finding the midpoint of any given 2 pair of points simply add the respective x coordinates with other x coordinate and the y coordinate with other y coordinate and divide them by 2

in your question it will be :

(3+1)/2 for the x coordinate of mid point i.e 2

[8+(-4)]/2 for the y coordinate of midpoint i.e 2

so coordinates of mid point of points (3,8) and (1,-4) will be (2,2)