SATMathematics Practice Test 1

Substituting 1,000 for a in the equation a=1,052+1.08t gives $1,000=1,052+1.08\mathit{t}$,and thus $\mathit{t}=\frac{-52}{1.08}\approx -48.15$. Of the choices given,$48°\mathit{F}$ is closest to $-48.15°\mathit{F}$.
Since the equation $\mathit{a}=1,052+1.08\mathit{t}$ is linear, it follows that of the choices given, $-48°\mathit{F}$ is the air temperature when the speed of a sound wave is closest to 1,000 feet per second.
Choices A, C, and D are incorrect, and might arise from errors in calculating $\frac{-52}{1.08}$or in rounding the result to the nearest integer.
For example, choice C could be the result of rounding $-48.15$ to $-49$ instead of $-48$.