Each day, Steve walked 1/12 mile more than the previous day. The first day he walked 1/12, the second day he walked 2/12 mile, the third day he walked 3/12 mile. On which day did the sum of his walks total at least 1 complete mule?

1st day = 1/12

2nd day = 2/12

3rd day = 3/12

4th day = 4/12

5th day = 5/12

6th day would be = 6/12

If it continues in that order, the sum of the walks would total 1 mile when:

They all add up to 12/12

Add = 1/12 + 2/12 + 3/12 + 4/12 = 10/12

That is still not up to 12/12

So we add up the 5th day also = 10/12 + 5/12 = 15/12 = 1 3/12 miles

So on the 5th day the sum of his walks total at least 1 completed mile.

At least 1 means 1 and above. As you can see the answer we got 1 3/12 is already more than 1.