ISEE Upper Level Math : How to find the solution to an equation

Study concepts, example questions & explanations for ISEE Upper Level Math

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Example Questions

Example Question #21 : How To Find The Solution To An Equation

Consider the following system:  and . What is the sum of  and ?

Possible Answers:

3

1

9

-1

-2

Correct answer:

1

Explanation:

We first need to line up the equations and solve for . If we add the equations together we get:

   

_______________

    

From this, we have . Now we plug  into either equation to find that . Thus, .

Example Question #21 : Algebraic Concepts

;   

Find the value of .

Possible Answers:

Correct answer:

Explanation:

When plugging in the values for  and , we find that the answer is :

Example Question #21 : Algebraic Concepts

A class has 25 students. If 60% of them are boys, how many students are girls?

Possible Answers:

9

8

10

20

15

Correct answer:

10

Explanation:

We know that 40% of the class are girls because 60% are boys. To express 40% as a fraction of the 25 total students, we set up a proportion to find the number of girls in the class. 

When solving for , we find that there are 10 girls in the class. 

Example Question #1 : How To Do Work Problems

Machine A can produce 4 books in 2 days. Machine B can produce 20 books in 4 days. How many books can machines A and B, working together, produce in 40 days?

Possible Answers:

280

960

10

200

120

Correct answer:

280

Explanation:

Through simplification, we can see that machine A produces 2 books a day and that machine B produces 5 books a day. If we multily each by 40 days and add them together, we find that together they can produce 280 books in 40 days:

Example Question #721 : Isee Upper Level (Grades 9 12) Mathematics Achievement

Adam has 3 siblings. When his mother bakes a cake, each of the 4 children is given ¼ of the cake. Adam only finished 1/3 of his share of cake. If the original cake had 12 slices, how many slices did Adam eat?

Possible Answers:

4

6

3

2

1

Correct answer:

1

Explanation:

Each of the children gets 1/4 of the cake. Taking 1/4 of 12 shows that each child gets 3 slices. If Adam finishes 1/3 of his share, then he has eaten one out of the 3 slices. 

Example Question #21 : Equations

Solve for :

Possible Answers:

18

21

7

42

63

Correct answer:

63

Explanation:

We first add 14 to both sides to get  by itself. This leaves us with . Divide both sides by  to see that the answer is

Example Question #722 : Isee Upper Level (Grades 9 12) Mathematics Achievement

Solve for :

Possible Answers:

5

23

69

15

7

Correct answer:

69

Explanation:

Subtract 22 from both sides, then multiply by 3 to solve for :

Example Question #723 : Isee Upper Level (Grades 9 12) Mathematics Achievement

What percent of 60 is 45?

Possible Answers:

75%

25%

45%

80%

50%

Correct answer:

75%

Explanation:

We need to set up a proportion to find out what percent of 60 is 45. When solving the proportion, we find that the answer is 75%.

 

 

Example Question #23 : Equations

Solve the set of equations

Possible Answers:

Correct answer:

Explanation:

Solve the second equation for y:

Substitute into the first equation:

Substitute into the first equation:

Solve for y:

Example Question #21 : Algebraic Concepts

Solve for .

Possible Answers:

Correct answer:

Explanation:

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