60 seconds because I have down this before and check it about a million time
Is there a picture with this?
Just use derivatives:
f'(x)= .48x-.96 = 0, x = 2, since the coeff of x^2 is +, this is a minimum
x=0 1989, so x = 2 is 1991! :)
<h3>
Answer: 50 mph</h3>
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Work Shown:
1/10 = 0.1
0.1 mile = 7.2 seconds
1 mile = 72 seconds (multiply both sides by 10)
1/72 mile = 1 second (divide both sides by 72)
3600/72 = 3600 seconds (multiply both sides by 3600)
50 miles = 3600 seconds
50 miles = 1 hour
The car's speed is 50 mph
Note: 1 hour = 60 min = 60*60 = 3600 seconds
3,500 is the best estimate if you multiply 7 by round 456 to 500 so 7x500=3,500
