Answer:
a. about 15.51 miles, rounded to 15.5 miles
b. about 31.02 miles, rounded to 31 miles
Step-by-step explanation:
Sunday Monday Tuesday Wednesday Thursday Friday Saturday
 10      20      40      80       160    320     640
 1280    2560     5120    10240    20480  40960   81920
81920/5280 = 15.51515151, rounded to the nearest tenth of a mile, 15.5 miles
Question b asks for how many miles in total has he ran. That means we have to add each of the values shown above and that equals to 163830 feet.
Divide that by 5280 and that equals 31.02 miles, rounded to the nearest tenth, 31 miles.
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