Coffee Math #1

How much cheaper is it to brew your own coffee?

Aeropress: $0.05/oz
Starbucks: $0.28/oz

Assumptions:

Cost of water:

`(($0.01)/(1 gal))((1 gal)/(128oz))(8 oz)=(($0.000625)/(8oz))`

Cost of filter paper:

`(($4.20)/(350fil.papers))= (($0.012)/(fil.paper)) `

Cost of beans:

`((12oz)/(1bag))((28.35g)/(1oz))((1serv.)/(17g))=~20serv.`
`(($7.45)/(1bag))((1bag)/(20serv.))= (($0.3725)/(1serv.))`

Putting it together:

Cost of Aeropress `=$0.3725+$0.012+$0.000625`
Cost of Aeropress: $0.385125
Cost per ounce: `($0.385125)/(8oz)=($0.048140625)/(oz )`

Easy part:

Cost of Starbucks tall: $3.14
Cost per ounce: `($3.14)/(12oz)=($0.2616)/(oz )`