Question

Consider a computer system have a processor-X which in general takes 4ns clock cycles but for ALU
branch instruction and memory operation takes 5 clocks cycles and 9 clock cycles, respectively. In
CPU, ALU 80% operations occurred, memory operations 25% occurred, branch instruction 30%
occurred. Other overheads over CPU execution take 1ns. What will be the average instructions
execution time if it is used in un-pipelined processor?
(a) 30ns
(b) 25.4ns
(c)23.4ns
(d)None of these