Below is a sorted stem-and-leaf diagram for the measured speeds (miles per hour) of 49 randomly chosen vehicles on highway I-80 in Nebraska. How many vehicles were traveling exactly the speed limit (70 mph)? Stem unit = 10 Leaf unit = 1 Frequency Stem Leaf 1 4 9 1 5 5 17 6 0 1 2 2 2 4 5 5 5 5 6 6 8 8 9 9 9 19 7 0 1 1 1 2 3 3 3 4 5 6 6 6 7 7 8 9 9 9 7 8 0 1 3 3 5 5 7 4 9 0 1 2 2 49