# SAT Math Multiple Choice Question 648: Answer and Explanation

Home > SAT Test > SAT Math Multiple Choice Practice Tests

### Test Information

- Use your browser's back button to return to your test results.
- Do more SAT Math Multiple Choice Practice Tests.

**Question: 648**

**3.** An information technology company estimates the cost of a project, in dollars, using the expression 240 1 3*nt*, where *n* is the number of computer servers working on the project and *t* is the total time, in hours, the project will take using *n* servers. Which of the following is the best interpretation of the number 3 in the expression?

- A. Each server costs the company $3 per hour to run.
- B. A minimum of 3 servers will work on the project.
- C. The price of the project increases by $3 every hour.
- D. Each server can work 3 hours per day.

**Correct Answer:** A

**Explanation:**

**A**

**Algebra (interpreting formulas) EASY-MEDIUM**

One way to analyze a formula is by "dimensional analysis." This is simply a way to check that the units in the formula represent what they are supposed to represent. For instance, we are told that the expression 240 + 3*nt* represents the cost, *in dollars*, of the project. This means that both terms in this expression must be in *dollars*. Notice, also, that *n* is the number of *servers* and *t* is the number of *hours*. Let's use a ? to represent the units of the number 3 in the expression 3*nt*. Translating the term into units, this gives us

(?)(servers)(hours) = $

Divide by (servers)(hours): _______________? =

In other words, it costs the company 3 dollars per hour per server.