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Question: A migratory bird travels a distance $v$ that is a multiple of 7. If $v^3$ is less than 3500, what is the maximum possible value of $v$?
Solution: Find the largest multiple of 7 where $v^3 < 3500$. Test $v = 7$: $343 < 3500$. $v = 14$: $2744 < 3500$. $v = 21$: $9261 > 3500$. Maximum is 14. \boxed{14}
Question: Two bird species migrate every 12 and 18 days. What is the least common multiple of their migration cycles?
Solution: Prime factors of 12: $2^2 \times 3$, of 18: $2 \times 3^2$. LCM is $2^2 \times 3^2 = 36$. \boxed{36}
Question: The arithmetic mean of five daily temperature readings for birds is 22°C. If four readings are 20, 21, 23, and 24, what is the fifth?
Solution: Total sum is $5 \times 22 = 110$. Sum of known values: $20 + 21 + 23 + 24 = 88$. The fifth value is $110 - 88 = 22$. \boxed{22}Question: Find the matrix $\mathbf{M}$ such that $\mathbf{M} \begin{pmatrix} 1 \\ 0 \end{pmatrix} = \begin{pmatrix} 2 \\ -1 \end{pmatrix}$ and $\mathbf{M} \begin{pmatrix} 0 \\ 1 \end{pmatrix} = \begin{pmatrix} 3 \\ 4 \end{pmatrix}$.
Solution: The matrix $\mathbf{M}$ is constructed by placing the images of the standard basis vectors as its columns. Thus, $\mathbf{M} = \begin{pmatrix} 2 & 3 \\ -1 & 4 \end{pmatrix}$. Verifying, $\mathbf{M} \begin{pmatrix} 1 \\ 0 \end{pmatrix} = \begin{pmatrix} 2 \\ -1 \end{pmatrix}$ and $\mathbf{M} \begin{pmatrix} 0 \\ 1 \end{pmatrix} = \begin{pmatrix} 3 \\ 4 \end{pmatrix}$, confirming correctness. $\boxed{\begin{pmatrix} 2 & 3 \\ -1 & 4 \end{pmatrix}}$
Question: An environmental consultant models a river's flow as the line $y = -\frac{1}{2}x + 5$. Find the point on this line closest to the pollution source at $(4, 3)$.
Solution: The closest point is the projection of $(4, 3)$ onto the line. The formula for the projection of a point $(x_0, y_0)$ onto $ax + by + c = 0$ is used. Rewriting the line as $\frac{1}{2}x + y - 5 = 0$, we compute the projection. Alternatively, parametrize the line and minimize distance. Let $x = t$, then $y = -\frac{1}{2}t + 5$. The squared distance to $(4, 3)$ is $(t - 4)^2 + \left(-\frac{1}{2}t + 5 - 3\right)^2 = (t - 4)^2 + \left(-\frac{1}{2}t + 2\right)^2$. Expanding: $t^2 - 8t + 16 
Question: A hydrologist models groundwater flow with vectors $\mathbf{a} = \begin{pmatrix} 2 \\ -3 \end{pmatrix}$ and $\mathbf{b} = \begin{pmatrix} 1 \\ 4 \end{pmatrix}$. Find the angle between these flow directions.
