You are tasked to design lifts for a multi$-$tenancy, prestige office building. The building has $30$ floors, excluding the ground floor which has no occupants. Each floor has a height of $3\mathrm{.}2$ m and an area of $900$ m$2.$ The floors are divided into two zones for two groups of lifts to serve. Zone $1$ covers the ground floor $($MT$)$ to the $15$th floor, and Zone $2$ the $16$th to the $30$th floor. Lifts for Zone $2$ should go non$-$stop from MT to the $16$th floor and then above.

$($a$)$ Plan the lifts for Zone $1.$

$($b$)$ Plan the lifts for Zone $2.$

$($c$)$ An indifference curve method is set up similar to that in the Intelligent Building Index to evaluate the design. It is divided into three elements, quantity of service, quality of service, and cost, each of a weight of $10.$ For the first element, the score goes from $100$ to $0$ continuously as the $\%$POP goes from $15\%($or more$)$ to $10\%($or less$).$ For the second, $100$ corresponds to a total time of $40$ s $($or less$)$ and $0$ corresponds to $70$ s $($or more$).$ For the last, $100$ corresponds to six floors per lift and $0$ corresponds to two floors. Calculate the overall score for the lift designs for the two zones respectively.

Background information: for prestrige office $,15-25$m$^2$ per person