Question

The optimal depth (d) for catching a certain type of fish satisfies the inequality 28|d – 350| – 7000 < 0. Which solution represents the range of depth that offers the best catch?
A 250 < d < 300
B 100 < d < 600
C 300 < d < 350
D 10 < d < 400

Answer 1

28|d – 350| – 7000 < 0

add 7000 to each side

28|d – 350|  < 7000

divide both sides by 28

|d – 350|  < 250

remove absolute value term on left so the right side becomes +/-
d-350 < +/- 250

now add 250 to 350 and subtract 250 from 350

250 +350 = 600
350-250 = 100

answer is: B 100 < d < 600