What is the average delay in Web caching?

I have been reading computer networks from Kurose & Ross and came around a topic called "web caching" upon reading further it described how the web caching can help to reduce the response time and substantially reduce the traffic on an institution's access link to the internet. here is the that part from the book. What I am not able to understand is how the average delay is calculated [0.4(0.01) seconds + 0.6 (2.01) seconds]. To be specific this 2.01 seconds came from where I am not able to get it. Thanks in advance.
P.s.: I can understand this might be a silly doubt to ask here but I prefer asking it anyway & sorry if the picture is a little blurry.