The mean and range of ten consecutive terms in an arithmetic progression are all 82. What is the first term in the sequence?
The mean and range of ten consecutive terms in an arithmetic progression are all 82.
What is the first term in the sequence?
\(\text{Let $a$ is the first term} \\ \text{Let $b$ is the last term}\)
\(\begin{array}{|lrcll|} \hline \text{mean:} & \dfrac{a+b}{2} &=& 82 \quad & | \quad \cdot 2 \\\\ & a+b &=& 2\cdot 82 \qquad (1) \\ \\ \text{range:} & b-a &=& 82 \qquad (2) \\ \hline \\ (1)-(2):& (a+b) - (b-a) &=& 2\cdot 82 - 82 \\ & a+b - b+a &=& 82 \\ & a+a &=& 82 \\ & 2a &=& 82 \quad & | \quad : 2 \\ & \mathbf{ a } & \mathbf{=} & \mathbf{41} \\ \hline \end{array}\)
The first term in the sequence 41