Answer: 15.7 minutes
Step-by-step explanation:
Let x be the time in the beginning (in minutes).
Given: The track team is trying to reduce their time for a relay race.
First they reduce their time by 
2.1 minutes.
Then they are able to reduce that time by 
10
If their final time is 3.96 minutes, then
Hence, their beginning time was 15.7 minutes.
23 +30 (15 feet each way) = 53
28 + 30 = 58
58 x 53 = 3074ft
The sound intensity of the Pile Driver is 39.5
or nearly 40 times the sound intensity of the jackhammer.
Given with Loudness in dB for pile driver = 112 dB
We have to convert it in terms of sound intensity.
First,
112dB/10 = 11.2
Then we'll use this as exponent of 10
(10)^(11.2) = 1.5849 * 10 ^ 11
Then use the equation of Watts per square meter to find the intensity:
I / (10^-12 W/m^2) =1.5849 * 10 ^ 11
I = sound intensity = 0.158
Then compare:
Sound intensity of Pile Driver/ Sound intensity of Jackhammer
(0.158) / (0.004)
= 39.5
or nearly 40 times the jackhammer.
