SOLUTION: This story problem really has me confused and I need some help with this this one please. The formula R = 0.075t + 3.85 can be used to predict the world record in the 1500 meter ru

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Question 254372: This story problem really has me confused and I need some help with this this one please. The formula R = 0.075t + 3.85 can be used to predict the world record in the 1500 meter run, t years after 1930. Determine an inequality that identifies the years in which the world record will be less than 3.7 minutes.
Solve for t
t > __ (Round to the nearest whole number.)
This translates to {Y|Y > __ }
Thanks so much!
Answer by ankor@dixie-net.com(22740) (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.
Determine an inequality that identifies the years in which the world record will be less than 3.7 minutes.
Solve for t
:
The way this is written makes no sense. R = -0.075t + 3.85 would makes some sense
From this we can surmise:
1 yr after 1930: R = 3.85 - .075 = 3.775 min which is what you would expect
:
Using that
-0.075t + 3.85 < 3.7
:
Subtract 3.85 from both sides
-0.075t < 3.7 - 3.85
:
-0.075t < -.15
t has to be positive, Multiply both sides by -1, this reverses the inequality sign
0.075t > .15
t >
t > 2 yrs, More than two years after 1930 (1932) the record would be < 3.7 min
:
:
Did this make sense to you now?