What would the payback period be for a robotic arm used by McDonald's for food

preparation?

A variety of robots were featured at the $2016$ National Restaurant Show that could be used for a variety

of tasks in restaurants. These robots are being introduced at the same time that we are experiencing an

on$-$going debate in the U$.$S$.$ about the merits of a national minimum wage of $$15$ per hour for every

worker. A former McDonald's USA CEO, Ed Rensi, recently said that purchasing a $$35,000$ robotic arm

would be cheaper than paying fast food workers $$15$ per hour for food preparation tasks like bagging

French fries.

For this hypothetical example, let's make the following assumptions:

Questions

What would the payback period be on a McDonald's robot used for food preparation?

What qualitative factors would McDonald's need to consider when deciding whether to

purchase robots to replace some of its food preparation workers?

Given the payback period, would net present value $($NPV$)$ or internal rate of return $($IRR$)$ be likely

to be useful tools for analyzing this decision? Support your response.