SAT Math : How to multiply integers

Study concepts, example questions & explanations for SAT Math

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Example Questions

Example Question #1 : How To Multiply Integers

F=ma in physics whereForce=mass\times acceleration.

If the mass is increased by 3 three times the original and the acceleration is increased by 7 times the original, how many times greater is the new force than the original force?

Possible Answers:

21

7

3

0

10

Correct answer:

21

Explanation:

We simply multiply the new mass by the new acceleration to obtain a new force that is 21 times greater than the original.

Example Question #2 : Operations

An office wants to buy 22 computers at $900 each. The budget is $20,000 and the tax on computers is 9%. How many computers can the office afford?

Possible Answers:

Correct answer:

Explanation:

The office can only afford 20 computers.

1.09 * 900 = $981 is the actual price of each computer, with tax.

Divide:

20,000/981 = 20.39

Since the office cannot purchase a partial computer, we round down to 20 computers.

Example Question #3 : Operations

A paint crew can paint  walls in  hours. At this rate, how many walls can the paint crew paint in  hours?

Possible Answers:

Correct answer:

Explanation:

First, divide  by  to determine how many walls the paint crew can paint in hour.

 divided by  is equal to .

Then, multiply this number by  hours.

Example Question #4 : Operations

Convert three yards to inches.

Possible Answers:

Correct answer:

Explanation:

To solve this problem, we need to know the conversions between yards to feet, and feet to inches.  Write their correct conversions.

Convert three yards to feet.

Convert nine feet to inches.

Example Question #2 : How To Multiply Integers

Calculate  in the following series:

Possible Answers:

Correct answer:

Explanation:

Each element is obtained from the previous one by alternating the following operations: multiplying by 5 and adding 6.

If we let  be the first element, then 

Solve for :

 

Example Question #2 : How To Multiply Integers

Janet can pick between 10 and 20 tomatoes in an hour. What is a possible amount of time for Janet to pick 120 tomatoes?

Possible Answers:

Correct answer:

Explanation:

Since Janet can pick between 10 and 20 tomatoes in an hour, there is a range for which she can pick 120 tomatoes. Therefore, to find the possible amount of time it will take Janet to pick 120 tomatoes set up two fractions.

The first fraction will use the rate of 10 tomatoes an hour.

Therefore, identifying the variables are as follows.

Substituting these into the fraction results in a possible time

The second fraction will use the rate of 20 tomatoes an hour.

Therefore, identifying the variables are as follows.

Substituting these into the fraction results in a possible time

Of the answer selections 6 hours would be the correct answer.

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