Algebra Demystified 2nd Ed

Chapter 9 linear inequaliTieS 323

Let x = number of hours per year the equipment is used

The monthly purchase costs amount to 12(2500) = 30,000 dollars annually.
The annual purchase cost = 30,000 + 20x.

Purchasecost<Rentcost

+<

30 000 20 45 000

30 000

,,

,

x

--

<

≤

<

30 000

20 15 000

15 000

20

750

,

,

,

x

x

x

The equipment should be used less than 750 hours annually to justify pur-
chasing it rather than renting it.

An amusement park sells an unlimited season pass for $240. A daily ticket
sells for $36. How many times would a customer need to use the ticket in
order for the season ticket to cost less than purchasing daily tickets?

Let x = number of daily tickets purchased per season

36 x = daily ticket cost

Seasonticketcost<dailyticketcost

240 36

24

< x

00

36

(^623)
<
<
x
x
A customer would need to use the ticket more than 623 times (or 7 or more
times) in order for the season ticket to cost less than purchasing daily
tickets.
Bank A offers a 621 % certificate of deposit and Bank B offers a 534 % cer-
tificate of deposit but will give a $25 bonus at the end of the year. What is
the least amount a customer would need to deposit at Bank A to make
Bank A’s offer no less attractive than Bank B’s offer?
Let x = amount to deposit
If x dollars is deposited at Bank A, the interest at the end of the year would
be 0.065x. If x dollars is deposited at Bank B, the interest at the end of