I am trying to create a formula that will assign a letter to a cell depending
on the amount in the cell next to where the letter will end up.
In the numbers below if 2.0 is in cell C5 I want to assign cell D5 an A. If
1.3 is in cell C6, I want to assign a B to cell D6. My formula looks like
this:

=if($C$5=c15,"A", $C$5=c16 and <c15,"B", $C$5<c16, "C")

This formula is not working.

2.0 (C5)
1.3 (C6)
0.6 (C7)
0.9 (C8)
0.3 (C9)
1.8 (C10)
1.4 (C11)

1.5 A (C15 and D15)
1.0 B (C16 and D16)
0.7 C (C17 and D17)

Would appreciate suggestions. Thanks!