$$a$)$ Determine the upper and lower limits for a $3$ standard deviation accuracy check.

Thompson Industries Monthly Supplier Report $-$ April

SupplierName SupNo SupCat Purchases Changes Quality On$-$Time Returns RejShip NewSup

Maverick Supplies $6071$ P $$38,870$ $$12,3495100\%0\%1$ N

Cowboy Pete's Lumber $6894$ P $$26,278$ $$730590\%0\%0$ N

ABC Metals $5054$ S $$23,309$ $$23,30930\%75\%3$ Y

Perkins Plastics $5528$ P $$28,519$ $$2,4124100\%3\%0$ N

Everything Brass $4413$ P $$29,002($$$4,769)5100\%0\%0$ N

Jones Aluminum & Copper $5858$ P $$16,260$ $$16,260450\%5\%3$ Y

Rick's Wrought Iron $9733$ S $$28,562($$$3,159)160\%80\%6$ N

Penelope's Paper Products $4718$ P $$26,187$ $$8,2263100\%12\%0$ N

Anthony's Adhesives $9944$ P $$22,961$ $$5,201490\%4\%0$ N

Columbus Manufacturing $1343$ S $$20,116$ $$10,9044100\%0\%2$ N

Smart Electronics, Inc. $4785$ P $$29,799$ $$29,799233\%50\%0$ Y

Watson Woodworking $2730$ S $$32,841($$$4,157)525\%1\%0$ N

Fred's Foam Molding $2949$ S $$24,333$ $$24,3335100\%0\mathrm{.}50\%0$ Y

Inpenetrable Insulation, Inc. $1443$ P $$25,246($$$4,395)415\%4\%0$ N

Suzy's Shipping Supplies $8039$ P $$24,378($$$602)550\%0\%0$ N