In parallelogram lmno, lm=4.12, mn=4,ln=5, and om=6.4. diagonals ln and om intersect at point r. what is the length of or?
a) 2
b) 2.06
c) 2.5
d) 3.2
e)12.8

We have given 
LM=4.12
MN=4
LN=5
OM=6.4
As diagonals LN and OM intersect at point R.
so we divide LN by 2 
we get 5/2=2.5
now using Pythagorean theorem 
OR^2= 4^2-2.5^2
OR^2=9.75
taking square root 
OR=3.12
so the right answer is d) 3.2