Question bank / Linear inequalities in one or two variables

Math · AlgebraMedium

Electrician A charges a $75\$75 service fee plus $60\$60 per hour of work. Electrician B charges a $110\$110 service fee plus $50\$50 per hour of work. For which numbers of hours of work, hh, is electrician B's total charge less than electrician A's?

A

h<3.5h < 3.5

B

h>3.5h > 3.5

C

h<18.5h < 18.5

D

h>18.5h > 18.5

Show answer and explanation

Answer: B

Electrician B costs less when 110+50h<75+60h110 + 50h < 75 + 60h. Subtract 50h50h and 7575 from both sides: 35<10h35 < 10h. So h>3.5h > 3.5.

Choice A gives the jobs for which electrician A costs less, which is the reverse of what the question asks.

Why the other choices are wrong

  • A. This reverses the comparison. For jobs shorter than 3.5 hours, electrician A is cheaper because of the lower fee.
  • C. This adds the two service fees instead of subtracting them, and it also reverses the direction.
  • D. This adds the two service fees, 75 + 110 = 185. The fees should be subtracted, 110 - 75 = 35.
Ask Owl about this questionNext question

Got it wrong? On SAT Owl, Owl looks at the answer you chose and explains the exact mistake, then gives you similar questions until it sticks. Get your predicted SAT score free, or take a free full-length practice test.