Question

The checking account fees for Banks A, B, C, and D are shown in the table below.

Monthly Service Fee Per-­Check Fee
Bank A $7.50 $0.25
Bank B None $0.50
Bank C $15.00 None
Bank D $10.00 $0.10
If a customer writes 23 checks per month, which bank will charge her the least in fees? Show your work.

Answer 1

Bank B is the right answer. It charges the least.

Explanation:

When 23 checks are signed from bank A:

Charges will be =
`7.50+0.25(23)` = $13.25

When 23 checks are signed from bank B:

Charges will be =
`0+0.50(23)` = $11.50

When 23 checks are signed from bank C:

Charges will be =
`15+0(23)` = $15

When 23 checks are signed from bank D:

Charges will be =
`10+0.10(23)` = $12.30

Hence, comparing all the banks, we can say that Bank B charges the least. So, Bank B is the correct option.

Answer 2

Bank B charges the least fee of $11.5

Explanation:

We know that, the general form of a linear equation is
`y=mx+b`, where m= rate and b= fixed constant.

The linear equations representing the account fee (y) for each bank,

where m = Per-Check Fee, b = Monthly Service fee and x = number of checks per month are given by,

Bank A:
`y=0.25x+7.5`

Bank B:
`y=0.50x`

Bank C:
`y=15`

Bank D:
`y=0.10x+10`

Since, the customer writes 23 checks per month. Then, x = 23.

Substituting x = 23 gives us the account fee for each bank is,

Bank A:
`y=0.25* 23+7.5=\$ 13.25`

Bank B:
`y=0.50* 23=\$ 11.5`

Bank C:
`y=\$ 15`

Bank D:
`y=0.10* 23+10=\$ 12.3`

Thus, Bank B charges the least fee of $11.5