Help. Police can estimate the speed of a vehicle before the brakes are applied using the formula 0.75d=s^2/30.25. where s is the speed in miles per hour and D is the length of the vehicles skid marks. what was the approximate speed of a vehicle that left a skid of 150 feet.
A)11 miles per hour
B)15 Miles per hour
C)58 miles per hour
D)67 miles per hour

I know its eitherC or D, I just am not sure how to find the answer! Thanks everyone!

Question

Help. Police can estimate the speed of a vehicle before the brakes are applied using the formula 0.75d=s^2/30.25. where s is the speed in miles per hour and D is the length of the vehicles skid marks. what was the approximate speed of a vehicle that left a skid of 150 feet. 
A)11 miles per hour
B)15 Miles per hour
C)58 miles per hour
D)67 miles per hour

I know its eitherC or D, I just am not sure how to find the answer! Thanks everyone!

anonymous · Answer

plug 150 in for d so

.75(150)=s^2/30.25

anonymous · Answer

$$0.75\times 150=\frac{s^2}{30.25}$$ solve for 
$s$

anonymous · Answer

112.5=s^2/30.45

Multiply both sides by 30.25

3,403.125=s^2

anonymous · Answer

s=the square root of 3403.125

anonymous · Answer

this equals 58.3363 mph

anonymous · Answer

I just got that as well! thank you so much for setting it up! it makes more sense now!