1B
2C
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9514 1404 393
Answer:
21.25 seconds
Step-by-step explanation:
In miles per second, the speed of the jet is ...
(720 mi/h)/(3600 s/h) = 1/5 mi/s
The speed of the sound is the same:
(1 mi)/(5 s) = 1/5 mi/s
Then the rate of closure between the airplane and the sound is ...
(1/5 mi/s) +(1/5 mi/s) = 2/5 mi/s
To find the time required to close a gap of 8 1/2 miles, we can use the relation ...
time = distance/speed
time = (8.5 mi)/(0.4 mi/s) = 21.25 s
The pilot will hear the thunder 21.25 seconds after the flash.
U set ST and SR equal
7x + 24 = 115
7x = 91
x = 13
Cross multiply...
Thus,
x(x+4)=(x+12)(x+8)
expand...
x^2+4x=x^2+8x+12x+96
Simply both sides of the equation.
x^2+4x=x^2+20x+96
simply further by adding ask like terms...
-16x=96
Solve for x by making x the subject.
therefore
x=-6.
