Solution for 3rd:-

Here To make 32:5 priority encoder from 4 given 8:3 priority encoders we must follow the following steps:-

Firstly we should take four 8:3 priority encoders and name them PE1, PE2, PE3, PE4 on the basis of the inputs given, Then we should connect all of them with 32 inputs 0-31 accordingly.

Then we should connect Ei of PE1, PE2, PE3 with E0 of  PE2, PE3, PE4  respectively.

Now take 5 inputs [00-04] and then take three And gates with 4 inputs and connect all outputs [00-02] to Ands of | A1 of all PEs, A2 of all PEs, A3 of all PEs|

respectively.

Now connect GS of PE2 and PE4 with AND gate and then connect that gate's output with output [o3].

Now connect GS of PE3 and PE4 with And the gate and then connect that gate's output with output [04].

So now our 32 inputs PE is ready.

Solution for 4th:-

Here 'X' state of logic output is used to indicate an invalid logic level while the Z-state of logic output is used to Indicating the Floating values.

If a BUS is driven to 0 & 1 by two enabled tristate buffers, the output is X-state while when enable of a tristate buffer is 0, Then the output is Z state(floating).

X- state logic output might change with a change in temperature, time but the Z-state output doesn't change.

Hence this is the solution.