201504 - Call 04

North Carolina
David thinks his car gets better mileage in the first half of a tank of gas than the second. He can drive 200 miles before the needle gets to half-full, but then only 100 miles between half and empty. Tom and Ray think his gauge isn’t calibrated exactly--when it reads half, he’s actually used more than half a tank. He can experiment by filling up the next time the needle is on half.