Consider the following multiple step experiment. A sales agent makes $3$ sales calls, at the end of each call a purchase is either made or not i$.$e$.,$ the two experimental outcomes for each call are $\{$purchase$,$ no purchase$\}.$ The following sample space describe the experiment:S$=\{($PPP$),($PPN$),($PNP$),($NPP$),($PNN$),($NPN$),($NNP$),($NNN$)\}.$ Consider the following events:E$1$ is the event that the agent makes no purchase.E$2$ is the event that the agent makes one purchase.E$3$ is the event that the agent makes two purchases.E$4$ is the event that the agent makes three purchases.Which one of the following statements is correct?a$.$The total number of experimental outcomes is $2.$b$.$P$($E$1)=0\mathrm{.}250$c$.$P$($E$2)=0\mathrm{.}250$d$.$P$($E$3)=0\mathrm{.}375$e$.$P$($E$4)=0\mathrm{.}375$