1. The problem statement, all variables and given/known data A highway is made of concrete slabs that are 15 m long at 20.0 degrees Celsius. (a) If the temperature range at the location of the highway is from -20.0degrees Celsius to +40.0degrees Celsius, what size expansion gap should be left (at 20.0degrees Celsius) to prevent buckling of the highway? 1. 3.8 mm 2. 1.6 mm 3. 3.6 mm 4. 4.2 mm 5. 2.6 mm (b) How large are the gaps at -20.0 degrees Celsius? 1. 9.5 mm 2. 11.7 mm 3. 11.0 mm 4. 12.7 mm 5. 10.8 mm 2. Relevant equations L=L0*a*T 3. The attempt at a solution I plugged in the values I have and I got: L=15*(12*10-6)*40 and got .0072 meters, or 7.2 millimeters, but that isn't one of the options. I can't do 'B' until I have A. Am I plugging in the values incorrectly? Help?