An instruction pipeline has five stages where each stage takes $$2$$ nanoseconds and all instructions use all five stages. Branch instructions are not overlapped, i.e., the instruction after the branch is not fetched till the branch instruction is completed. Under ideal conditions.

(a) Calculate the average instruction execution time assuming that $$20$$% of all instruction executed are branch instructions. Ignore the fact that some branch instructions may be conditional.

(b) If a branch instruction is a conditional branch instruction, the branch need not be taken. If the branch is not taken, the following instructions can be overlapped. When $$80$$% of all branch instructions are conditional branch instructions, and $$50$$% of the conditional branch instructions are such that the branch is taken, calculate the average instruction execution time.

An instruction pipeline consists of $$4$$ stages: Fetch (F), Decode field (D), Execute (E), and Result-Write (W). The $$5$$ instructions in a certain instruction sequence need these stages for the different number of clock cycles as shown by the table below.

Find the number of clock cycles needed to perform the $$5$$ instructions