To compute the rate of snow falling during the first snowfall we have to compute the slope of the first line of the given piecewise graph.
Recall that the slope of a line that passes through two given points is:
Notice that the first line of the given piecewise graph passes through the points (0,1) and (4,7), therefore its slope is:
In this case, the above result means that the rate of snow falling during the first snowfall is:
3 inches every 2 hours.
Answer: 3 inches every 2 hours.