As long as the mass of the chip is evenly distributed on each side, whatever times you flip the chip,
The probability will always be 50%
First, we count how far reached the Nell:
3,5 * 16 = 56 miles
Secondly, we count how far reached the Kristin:
3,5 * 18 = 63 miles
Now we expect the difference in the distance between them:
63 - 56 = 7 miles
The results that Kristin about seven miles driven more than Nell.