## College Algebra (6th Edition)

1. Degree days in January 1 = 23 Degree days in January 2 = 25 The temperature rose 2 degrees for every day 2. Thus the sequence in 23,25,27 ... 41 Use Formula for adding numbers in a series $Sum_{n} =\frac{n}{2}(a_{1}+a_{n})$ In other words, add the last number and the 1st number and then multiply that by the total number of numbers in the sequence, and divide that by 2 $Sum_{10} =\frac{10}{2}(23+41)$ = $5\times64$ = 320