4. Simplify the following expressions by means of a three-variable K-Map (a) XY +Z+XYZ 5. Simplify the following expressions by means of a four-variable K-Map (a) AD +BD+BC+ABD (b) ABC+CD+BCD+BC 6. Propose and solve your own boolean expression problem 7. Heart-Rate Monitor sensors output zero (0) if they are within safety range. An alarm will sound if either sensor indicates an unsafe condition is present. Set-up the appropriate truth table, simplify using K-maps. Implement, using LogiSim, the simplified logic circuit with optial number of logic gates. 8. Hurricane Detector Three LEDs (one red, one green, one blue) turn on when a number 0-7 is passed through. Red turns on with even numbers, green turns on with odd numbers, blue turns on with multiples of 3. Zero means they are all off, seven means they are all on. Set-up the appropriate truth table, simplify using K-maps. Implement, using LogiSim, the simplified logic circuit with optimal number of logic gates