Big Ideas Math Algebra 2, 2014
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Big Ideas Math Algebra 2, 2014 View details
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Exercise 25 Page 326

Practice makes perfect
a

We will begin by analyzing the compound interest formula.

A= P(1+r/n)^(n t) The components of the formula can be described as shown below. A:& amount in the account after t years P:& initial amount r:& annual rate written as a decimal n:& number of periods t:& number of yearsNow that we know the meaning of each component in the formula, let's determine the values of each component using the advertisements.

CD Specials Anytown Community Bank
Initial Amount ($) P_1=1500 P_2=2000
Annual Rate r_1=0.02 r_2=0.03
Number of Years t_1=3 t_2=5

Now, we can continue by finding the amount in CD Specials at the end of its term. Notice that the interest is compounded monthly, so the number of periods will be 12.

A=P(1+r/n)^(nt)
A= 1500(1+0.02/12)^(12( 3))
â–¼
Simplify right-hand side
A=1500(1+0.02/12)^(36)
A=1500(1+0.00166...)^(36)
A=1500(1.00166...)^(36)
A=1500(1.06178...)
A=1592.67527...
A≈ 1592.68

The amount is about $1592.68. But subtracting the initial amount from the final amount, the amount of interest can be found. 1592.68-1500=92.68 Therefore, the amount of interest is about $92.68. Proceeding in the same way, we can find the amount in Anytown Community Bank.

P r n t P(1+r/n)^(nt) A
CD Specials 1500 0.02 12 3 1500(1+0.02/12)^(12( 3)) 1592.68
Anytown Community Account 2000 0.03 12 5 2000(1+0.03/12)^(12( 5)) 2123.23

Next, we will find the amount of interest.

A P Interest
CD Specials 1592.68 1500 1592.68-1500=92.68
Anytown Community Account 2123.23 2000 2123.23-2000=123.23

b

We can examine the benefits and drawbacks of the accounts under three topics which are time, deposit, and interest.

  • CD Specials has the benefits of smaller segment of time and smaller deposit. However, it has a drawback of smaller interest.
  • Anytown Community Bank has the benefit of greater interest. However, it has the drawbacks of greater segment of time and greater deposit.