Chapter 13
Exercise 10:
Hint: Note that ' is synonymous with the overbar, the Boolean representation for the NOT operation.

Your truth table might start out looking like this:

A	B	A'	C=  AB	D=  A'B	C+D
0	0
0	1
1	0
1	1

Ans: The final column in the table constructed in the hint is identical to B.

Exercise 11:
Hint: Your truth table might start out looking like this:

A	B	C	B'	C'	D=  BC	E=  C'B	F=  B'A	D+E+F	A+B
0	0	0
0	0	1
0	1	0
0	1	1
1	0	0
1	0	1
1	1	0
1	1	1

Ans: see link.

Exercise 18:
Hint: It would appear that the circuit was incorrectly drawn! Otherwise most of the gates are redundant...

x3	x2	x1	x3'	x2'	A=  x3'x2'x1	B=  A	A+B
0	0	0
0	0	1
0	1	0
0	1	1
1	0	0
1	0	1
1	1	0
1	1	1

Ans: The only true outcome is when x₃=0, x₂=0, and x₁=1.

Exercise 21:
Hint: Pick names for the four inputs; suggestions would be H₁, F₁, H₂, and F₂, for height and flow, respectively, for the two tanks.
Consider using false (0) to indicate an acceptable sensor reading and true (1) to indicate a reading beyond an accepted level.

Ans: see link.