All PSAT Math Resources
Example Questions
Example Question #1 : How To Find Compound Interest
Donna wants to deposit money into a certificate of deposit so that in exactly ten years, her investment will be worth $100,000. The interest rate of the CD is 7.885%, compounded monthly.
What should Donna's initial investment be, at minimum?
More information is needed to answer the question.
The formula for compound interest is
where is the initial investment, is the interest rate expressed as the decimal equivalent, is the number of periods per year the interest is compounded, is the number of years, and is the final value of the investment.
Set (monthly = 12 periods), and , and evaluate :
The correct response is $45,569.99.
Example Question #1 : How To Find Compound Interest
Tom invests , in a savings account with an annual interest rate of . If his investment is compounded semiannually, how much interest does he earn after years?
In order to find the interest earned, used the compound interest formula
where represents the number of times the account is compounded each year, and represents the interest rate expressed as a decimal.
The account is worth $16882.63 after two years. Therefore Tom earns $1882.63 in interest.
Example Question #2 : Pattern Behaviors In Exponents
If ax·a4 = a12 and (by)3 = b15, what is the value of x - y?
-4
3
-9
-2
6
3
Multiplying like bases means add the exponents, so x+4 = 12, or x = 8.
Raising a power to a power means multiply the exponents, so 3y = 15, or y = 5.
x - y = 8 - 5 = 3.
Example Question #1 : How To Find Patterns In Exponents
If p and q are positive integrers and 27p = 9q, then what is the value of q in terms of p?
(3/2)p
p
3p
(2/3)p
2p
(3/2)p
The first step is to express both sides of the equation with equal bases, in this case 3. The equation becomes 33p = 32q. So then 3p = 2q, and q = (3/2)p is our answer.
Example Question #2 : How To Find Patterns In Exponents
Simplify 272/3.
9
125
3
27
729
9
272/3 is 27 squared and cube-rooted. We want to pick the easier operation first. Here that is the cube root. To see that, try both operations.
272/3 = (272)1/3 = 7291/3 OR
272/3 = (271/3)2 = 32
Obviously 32 is much easier. Either 32 or 7291/3 will give us the correct answer of 9, but with 32 it is readily apparent.
Example Question #1 : How To Find Patterns In Exponents
If and are integers and
what is the value of ?
To solve this problem, we will have to take the log of both sides to bring down our exponents. By doing this, we will get .
To solve for we will have to divide both sides of our equation by to get .
will give you the answer of –3.
Example Question #4 : How To Find Patterns In Exponents
If and , then what is ?
We use two properties of logarithms:
So
Example Question #571 : Algebra
Evaluate:
, here and , hence .
Example Question #5 : How To Find Patterns In Exponents
Solve for
None of the above
=
which means
Example Question #6 : How To Find Patterns In Exponents
Which of the following statements is the same as:
Remember the laws of exponents. In particular, when the base is nonzero:
An effective way to compare these statements, is to convert them all into exponents with base 2. The original statement becomes:
This is identical to statement I. Now consider statement II:
Therefore, statement II is not identical to the original statement. Finally, consider statement III:
which is also identical to the original statement. As a result, only I and III are the same as the original statement.