7th Grade Math

Preparing for

Standardized Tests

Multiple Choice: Using the Answer Choices

Sometimes you can find the correct answer more quickly by substituting each

answer choice into the problem.

Renata earns $7.50 per hour babysitting. She spent $16 of the total amount

that she earned this week on a new CD and had $29 left over. Use the

equation below to find h, the number of hours she babysat this week.

7.5h - 16 = 29

A. 1.7 hours C. 6 hours

B. 3.9 hours D. 13 hours

Substitute each answer choice into the equation until you find the correct

solution.

7.5(1.7) - 16 = 29 Substitute 1.7 for h.

12.75 - 16 = 29

• 3.25 ≠ 29 
  7.5(3.9) - 16 = 29 Substitute 3.9 for h.
  29.25 - 16 = 29
  13.25 ≠ 29 
  7.5(6) - 16 = 29 Substitute 6 for h.
  45 - 16 = 29
  29 = 29 
  Since this is a true sentence, 6 is the solution of the equation.
  So, the correct answer is C.

The Berk family camped for 6 nights and paid a total of $89.

Their total cost, which includes an admission fee of $5 and

the cost per night d, can be represented by 6d + 5 = 89.

What was the cost per night?

F. $14.00 H. $15.67

G. $14.83 I. $16.60

Once you find the solution,

you do not need to

substitute the

remaining answer

choices into the

equation.

r

Preparing for Standardized Tests 259

259_261_C04STP_895130.indd 259 12/31/09 4:08 PM