Police use a formula $s=S \sqrt{\frac{1}{L}}$, where Sis the test- car speed and $L$ is the test- skid length, to find the actual speed s in an accident which left a skid mark of l. Find the speed (nearest whole mph) when $\mathrm{S}=45 \mathrm{mph}, \mathrm{l}=150 \mathrm{ft}, \mathrm{L}=100 \mathrm{ft}$.
A) $55 \mathrm{mph}$
B) $95 \mathrm{mph}$
C) $37 \mathrm{mph}$
D) $68 \mathrm{mph}$

Question

Quizplus · Accepted Answer

Substituting $S = 45$ mph and $L = 100$ ft into the formula $s = S \sqrt{\frac{1}{L}}$ gives $s = 45 \sqrt{\frac{1}{100}} = 45 \times \frac{1}{10} = 4.5 \times 10 = 45$ mph, which is not directly an option. The correct application should be $s = S \sqrt{\frac{l}{L}} = 45 \sqrt{\frac{150}{100}} = 45 \sqrt{1.5} \approx 55$ mph, rounding to the nearest whole number.

Police Use a Formula s=S1Ls=S \sqrt{\frac{1}{L}}s=SL1​​ , Where Sis the Test- Car Speed And

Police Use a Formula $s=S \sqrt{\frac{1}{L}}$ , Where Sis the Test- Car Speed And