> How do you do this? I already have a) i just need to find b)?

How do you do this? I already have a) i just need to find b)?

Posted at: 2014-12-18 
Below is the statistic of instructions running on a computer /CPU :

Operation Frequency Cycles per operation

ADD 40% 3

Load 10% 5

Store 10% 5

Branch 20% 4

Others 20% 5

(a). What is the CPI of the machine for this program?

(b). What is the percentage of CPU time used for ADD instruction?