dave13 wrote:

saswata4s wrote:

On January 1, Jamie did one sit-up. On each of the next 364 days, she did one more than on the previous day. What was the total number of sit-up she did in 365 days?

(A) 66430

(B) 66795

(C) 66978

(D) 67160

(E) 132860

SUM OF N TERMS = \(\frac{n}{2} (2a+(n-1)d)\)

\(a\) = 1 the first term

\(d\) = 1 distance

\(n\) = 364 how many terms to add up

\(\frac{364}{2} (2*1+(364-1)1)\)= 365*182 = 66,430

now i need to add 365, cause one sit-up was not counted. 66,430 +365 = 66,795

pushpitkc is it valid solution ?

Hi

dave13Most of the stuff is correct - the formula is correct, a = d = 1(is correct), but n = 365(it's not 364)

Substituting values, we get \(\frac{365}{2}(2+(365-1)1) = \frac{365*366}{2} = 365*183\)

So, you will get the answer 66795 as it is - without having to add one sit-up which was counted

Hope this helps you!

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