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HOW TO SOLVE THIS PROBLEM HELP?
Andrea runs 4 miles every day, but she wants to increase her distance in order to run a 26 mile marathon. She decides to add 2 miles each day to her distance until she achieves her goal. If she starts with 6 miles today, how many miles will she have run in total, by the time she achieves her 26 mile goal? The correct answer is 176 miles.
2 Answers
- KrishnamurthyLv 74 weeks ago
Andrea runs 4 miles every day, but she wants to increase her distance
in order to run a 26 mile marathon.
She decides to add 2 miles each day to her distance until she achieves her goal.
If she starts with 6 miles today, how many miles will she have run in total,
by the time she achieves her 26 mile goal?
6 + 8 + 10 + 12 + 14 + 16 + 18 + ... + 26
sum_(n=1)^11 2 (n + 2) = 176 miles
The correct answer is 176 miles.
- stanschimLv 71 month ago
6 + 8 + ...+ 26
It takes 11 terms to get to 26. You can calculate this by:
a(n) = a(1) + (n-1)d
26 = 6 + (n-1)2
20 = 2n - 2
22 = 2n
n = 11
To find the cumulative sum:
S = [(a(1) + a(12)](n/2) = [6 + 26](11/2) = 16(11) =176
