Question

Janine is considering buying a water filter and a reusable water bottle rather than buying bottled water. Will doing so save her money?

First, determine what information you need to answer this question, then click here to display that info (along with other info).

• How much water does Janine drink in a day? She normally drinks 3 bottles a day, each 16.9 ounces.
• How much does a bottle of water cost? She buys 24-packs of 16.9 ounce bottles for $2.89.
• How much does a reusable water bottle cost? About $10.
• How long does a reusable water bottle last? Basically forever (or until you lose it).
• How much does a water filter cost? How much water will they filter?
  • A faucet-mounted filter costs about $28 and includes one filter cartridge. Refill filters cost about $33 for a 3-pack. The box says each filter will filter up to 100 gallons (378 liters)
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Which option is cheapest over one year (365 days)? Select an answer Water bottles faucet-mount filter

The cheapest option saves her $ over a year.

Give your answer to the nearest cent. Pro-rate the costs (so if you only use half of a filter pack, only count half the cost).

Answer 1

With the data given;

We 1st find the amount of water she drinks in a year.

Amount of water consumed in a year=amount of water consumed in a day *365

= (16.9*3)*365

=50.7*365

=18,505.5 ounces.

Next, we see the cost of bottles.

Cost of water per day=cost per bottle*number of bottles

-= ($2.89/24=0.1204)*3

= 0.3612

She drinks a total of 18,505.5 ounces in a year which is equal to 1095 of the 16.9-ounce bottles.

Cost of bottles water per year = cost of bottled water * number of bottles consumed in a year

= 0.1204*1095

=131.236

Thus with buying bottles it will cost her 131.236 for one year.

OPTION 2

Cost of the reusable bottle = $10

Cost of filter with 1 cartilage= $28

Cost of a single refill=$11 (pack of 3=$33, hence 1=$11)

Filtering capacity for 1 cartilage= 378 liters or 12781.7 ounces

Amount of water consumed in a year = 18,505.5

Amount of water that can be filtered by 1 cartilage already in the filter= 12781.7

Remaining 5123.8 ounces will require a new refill

Cost of using water filter=cost of bottle +cost of filter +cost of refill

Since only one cartilage is used to filter the remaining 5723.8 ounces of water

= 10+28+11

= 49

Thus, the water filter will cost her $49 for a year.

The water filter is a cheaper option. She will be saving;

=Cost of buying water-water filter

=131.236-49

= $82.236