Suppose you ride your bike uphill to work at a speed of at least x mph. Going downhill on the way home, your speed is 5 mph faster. Your average speed to and from work is at least 12 mph. Which is the correct inequality to model the situation?

Question

Mathematics

Emilee Rodriguez

4 October, 11:45

Suppose you ride your bike uphill to work at a speed of at least x mph. Going downhill on the way home, your speed is 5 mph faster. Your average speed to and from work is at least 12 mph. Which is the correct inequality to model the situation?

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Answers (2)

Know the Answer?

Walter Ashley · Answer 1

The answer would be 4 mph.

Let x = rate on the return trip Then, x+8 = rate in the other direction Distance = (Rate) (Time), so Time = (Distance / (Rate) Time to campus + Time from campus = 7/3 So, 7 / (x+8) + 7/x = 7/3 Divide both sides by 7: 1 / (x+8) + 1/x = 1/3Multiply both sides by the LCD, 3x (x+8), to get3x + 3 (x+8) = x (x+8) Simplifying, we have 6x + 24 = x2 + 8x now just combine like terms and simplify.

Abraham Harding · Answer 2

The answer is C.

1/x + 1/x+5 greater or equal to 2/12