# Algebra II : Using e

## Example Questions

← Previous 1

### Example Question #1 : Using E

On the day of a child's birth, a sum of money is to be invested into a certificate of deposit (CD) that draws 6.2% annual interest compounded continuously. The plan is for the value of the CD to be at least $20,000 on the child's 18th birthday. If the amount of money invested is to be a multiple of$1,000, what is the minimum that should be invested initially, assuming that there are no further deposits or withdrawals?

Explanation:

If we let  be the initial amount invested and  be the annual interest rate of the CD expressed as a decimal, then at the end of  years, the amount of money  that the CD will be worth can be determined by the formula

Substitute , and solve for .

The minimum principal to be invested initially is $6,551. However, since we are looking for the multiple of$1,000 that guarantees a minimum final balance of $20,000, we round up to the nearest such multiple, which is$7,000 - the correct response.

### Example Question #2 : Using E

Twelve years ago, your grandma put money into a savings account for you that earns  interest annually and is continuously compounded. How much money is currently in your account if she initially deposited  and you have not taken any money out?

$24,596$21,170

$10,778$8,103

$81,030 Correct answer:$24,596

Explanation:

1. Use  where  is the current amount,  is the interest rate,  is the amount of time in years since the initial deposit, and  is the amount initially deposited.

2. Solve for

You currently have \$24,596 in your account.

### Example Question #3 : Using E

Solve for

Explanation:

Step 1: Achieve same bases

Step 2: Drop bases, set exponents equal to eachother

Step 3: Solve for x

### Example Question #4 : Using E

Solve for

Explanation:

Step 1: Achieve same bases

Step 2: Drop bases, set exponents equal to eachother

Step 3: Solve for

### Example Question #5 : Using E

Solve for

Explanation:

Step 1: Achieve same bases

Step 2: Drop bases and set exponents equal to eachother

Step 3: Solve for

### Example Question #6 : Using E

Solve for

Explanation:

Step 1: Achieve same bases

Step 2: Drop bases and set exponents equal to eachother

Step 3: Solve for

### Example Question #7 : Using E

Solve for

Explanation:

Step 1: Achieve same bases

Step 2: Drop bases, set exponenets equal to eachother

Step 3: Solve for

### Example Question #8 : Using E

Solve:

Explanation:

To solve , it is necessary to know the property of .

Since  and the  terms cancel due to inverse operations, the answer is what's left of the  term.

### Example Question #9 : Using E

Simplify:

Explanation:

In order to eliminate the natural log on both side, we will need to raise both sides as a power with a base of .  This will cancel out the natural logs.

The equation will become:

Subtract  on both sides.

Simplify both sides.

Divide both sides by negative five.

### Example Question #10 : Using E

Simplify:

Explanation:

In order to cancel the natural logs, we will need to use  as a base and raise both raise both sides as the quantity of the power.

The equation becomes:

Subtract  and add three on both sides.

The equation becomes:

Use the quadratic equation to solve for the possible roots.