SOLUTION: The formula R= -0.075t+3.85 can be used to predict the world record in the 1500 meter run, t years agter 1930. Determining an inequality that identifies the years in which the worl

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Question 134857: The formula R= -0.075t+3.85 can be used to predict the world record in the 1500 meter run, t years agter 1930. Determining an inequality that identifies the years in which the world record will be less than 2.8 minutes. Sovle for t. Thanks for your time.
Found 2 solutions by vleith, stanbon:
Answer by vleith(2983) About Me  (Show Source):
You can put this solution on YOUR website!
Given: R=+-0.075t%2B3.85+
At some year, the time will get below 2.8 minutes
2.8+%3E+-0.075t%2B3.85+
%282.8-3.85%29+%3E+-0.075t+
Remember to swap the sign when multiplying or dividing by a negative
+%28%28-1.05%29%2F%28-0.075%29%29+%3C+t+
+14+%3C+t+
So any year > 1930 + 14 will do it
+t+%3E+1944+

Answer by stanbon(75887) About Me  (Show Source):
You can put this solution on YOUR website!
The formula R= -0.075t+3.85 can be used to predict the world record in the 1500 meter run, t years after 1930. Determining an inequality that identifies the years in which the world record will be less than 2.8 minutes. Solve for t. Thanks for your time.
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2.8 > -0.075t+3.85
-0.075t < -1.05
t > 14
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R will be less than 2.8 after 1930+14 = 1944
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Cheers,
Stan H.