Praxis Core Math

Question

This final ets question really threw me for a loop. Logically speaking the answer should be 6 + 1, but that was not listed as one of the answer choices. I guessed an answer and still got it wrong. What do you think? Can anyone show a viable solution set?

 

QUESTION

On a map that is drawn to scale, 6 inches represents a distance of d miles. Which of the following represents the distance, in inches, of d+1 miles on the map?

• d(d+1)/6
• 6(d+1)/d
• d+1/6d
• 6d/d+1
• 6/d(d+1)

 

Answer 1

Set up a proportion:

 

     d/6 = (d+1)/x

 

where x is the distance in inches on the map that represents d+1 miles.  Now cross multiply:

 

     dx = 6(d+1)

 

Divide both sides by d:

 

     x = 6(d+1)/d