Problem $3-14($Algo$)$

Demand for stereo headphones and music players for joggers has caused Nina Industries to grow almost $50$ percent over the past

year. The number of joggers continues to expand, so Nina expects demand for headsets to also expand, because, as yet, no safety

laws have been passed to prevent joggers from wearing them. Demand for the players for this year was as follows:

a$.$ Using linear regression analysis, what would you estimate demand to be for each month next year? Using a spreadsheet, follow the

general format in Exhibit $3\mathrm{.}7.$

Note: Do not round Intermedlate calculatlons. Round your answers to $2$ decimal places.

b$.$ To be reasonably confident of meeting demand, Nina decides to use $2$ standard errors of estimate for safety. How many additional

units should be held to meet this level of confidence?

Note: Do not round Intermedlate colculatlons. Round your answer to the nearest whole number.

Additional units