Question 828604: Brittany is a mountain climber who has reached the peak of a certain mountain. She is now ready to get back to the base of the base of the mountain and will return to it at a constant rate. Forty-five seconds after she began her descent, she is exactly a half mile above the ground. She is exactly 1,416 feet above the ground 198 seconds after her descent. Before she left the peak, Brittany predicted she will be at the base of the mountain in seven minutes. How far off (in minutes and seconds) is Brittany from her prediction ?
Answer by TimothyLamb(4379)   (Show Source):
You can put this solution on YOUR website! ---
given:
(45, 5280/2)=(45, 2640)
(198, 1416)
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to solve the linear equation, copy and paste this (the two given points):
45, 2640, 198, 1416
into the "Two-Point form: x1 y1 x2 y2" input box here: https://sooeet.com/math/linear-equation-solver.php
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answer:
x-intercept = (375, 0)
y-intercept = (0, 3000)
slope = -8
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the slope-intercept form:
y = -8x + 3000
where:
x = time in seconds
y = altitude in feet
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0 = -8x + 3000
8x = 3000
x = 375
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7*60 - 375 = 45
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answer:
she will be on the ground in 375 seconds (or 6 minutes and 15 seconds), which means that her descent time will be 45 seconds less than than her prediction.
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