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PS question

by zozo123 » Mon May 21, 2007 8:42 am
In the first week of the year, Nancy saved $1. In each of the next 51 weeks, she saved $1 more than she had saved in the previous week. What was the total amount that Nancy saved during the 52 weeks?
A. $1,326
B. $1,352
C. $1,378
D. $2,652
E. $2,756


How can we find the sum of a list (1+2+3+4+...) ? thanks
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by Cybermusings » Mon May 21, 2007 8:58 am
In the first week of the year, Nancy saved $1. In each of the next 51 weeks, she saved $1 more than she had saved in the previous week. What was the total amount that Nancy saved during the 52 weeks?
A. $1,326
B. $1,352
C. $1,378
D. $2,652
E. $2,756

In first week $1; in second week 2; in third week 3 hence in the 52nd week she would save $52
This is simple arithmetic progression; use the formula to find the sum of an arithmetic progression

{n [2a1 + (n-1)d]}/2
= {52[2 + (52-1)*1]}/2
= {52 [2+51]}/2
= 52*53 / 2
= 1378
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by drhomler » Mon May 21, 2007 9:49 am
In the generic version of the formula what do a1 and d represent?
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by Cybermusings » Mon May 21, 2007 10:38 am
a1 represents the first term of the sequence and d represents the difference between 2 consecutive terms
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by drhomler » Mon May 21, 2007 11:21 am
Thank you that was very helpful. I appreciate it, and hopefully I get one like this on the exam.
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by zozo123 » Tue May 22, 2007 1:04 am
Cybermusings, thanks very much!!!
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