A Company's Chief Operating Officer (COO) Keeps Track of the Mileage

Multiple Choice

A company's Chief Operating Officer (COO) keeps track of the mileage on her trips from her office at corporate headquarters to the company's off-site manufacturing facility and its nearby suppliers. The stem-and-leaf display of the data for one year is below. How many trips were used in this display?

A) 7
B) 9
C) 10
D) 11
E) 12