Customers tend to exhibit loyalty to product brands but may be persuaded through clever marketing and advertising to switch brands. Consider the case of threee brands: A$,$ B and C$.$ Customers "unyielding" loyalty to a given brand is estimated at $75\%,$ giving the competitors only a $25\%$ margin to realize a switch. For Brand A customers, the probabilities of switching to brands B and C or $\mathrm{.}1$ and $\mathrm{.}15.$ Customers of Brand B are likely to switch to A and C with probabilities $\mathrm{.}2$ and $\mathrm{.}05.$ Brand C customers wswitch to Brands A and B with equal probabilities. How long on average will it take for a Brand A customer to switch to Brand B$?$ To Brand D$?$