The midpoint of (x1,y1) and (x2,y2) is

just average them
(4,1) and (-2,4)
the midpoint is

(1,-1.5)
I would say the object will float because the density of water is 999.99kg/m which is slightly less than 1g but still more than the object.
The answer is nine. You can write 27 as 27/1. From there, just multiply the fractions.
27/1 x 1/3 = 9
X is equal to 12
This is because 5 was multiplied and 6 making 30. So you have to multiply 2 and 6 making x 12. Hope that makes sense
ANSWER
2
To find 1% of something (1/100 of something), divide by 100.
1% of 200 is 2.