2002 AMC 10P Problems/Problem 2

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Problem 2

The sum of eleven consecutive integers is $2002.$ What is the smallest of these integers?

$\text{(A) }175 \qquad \text{(B) }177 \qquad \text{(C) }179 \qquad \text{(D) }180 \qquad \text{(E) }181$

Solution 1

We can use the sum of an arithmetic series to solve this problem.

Let the first integer equal $a.$ The last integer in this string will be $a+10.$ Plugging in $n=11, a_1=a,$ and $a_n=a+10$ into $\frac{n(a_1 + a_n)}{2}=2002,$ we get:

\begin{align*} \frac{11(a + a+10)}{2}&=2002 \\ 11(2a+10)&=4004 \\ 2a+10&=364 \\ 2a&=354 \\ a&=177\\ \end{align*}

Thus, our answer is $\boxed{\textbf{(B) }177}$

Solution 2

We can directly add everything up since $1 + 2 + \; \dots \; + 10$ is so little.

Similar to the first solution, let the first integer equal $a.$ The last integer in this string will be $a+10.$

\begin{align*} a + (a + 1) + (a + 2) + \; \dots \; + (a + 10) &= 2002 \\ 11a + (1 + 2 + \; \dots \; + 10) &= 2002 \\ 11a + 55 &= 2002 \\ 11a &= 1947 \\ a &= \frac{1947}{11} \\ a &= 177 \\ \end{align*}

Thus, our answer is $\boxed{\textbf{(B) }177}$

See Also

2002 AMC 10P (ProblemsAnswer KeyResources)
Preceded by
Problem 1
Followed by
Problem 3
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All AMC 10 Problems and Solutions

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