Solve the below problem:
Q: An article in Proceeding of the 33rd International ACM SIGIR Conference on Research and Development in Information Retrieval ["Understanding Web Browsing Behaviors Through Weibull Analysis of Dwell Time"] proposed that a Weibull distribution can be used to model Web page dwell time (the length of time a Web visitor spends on a Web page). For a specific Web page, the shape and scale parameters are 1 and 300 seconds, respectively. Determine the following:
(a) Mean and variance of dwell time
(b) Probability that a Web user spends more than four minutes on this Web page
(c) Dwell time exceeded with probability 0.25