Asked by Anonymous
Ed is planning daily walking workouts on the same distance of 12 km in the morning and in the evening. Usually he is walking at constant rate, however he planned his rate to be 1 km/h more in the morning than in the evening. Given he is willing to spend 5 hours and 24 minutes daily on these workouts, what should his morning rate be, in km/h?
Answers
Answered by
Anonymous
5 km/h
Answered by
henry2,
r = X km/h in the mornings.
r = x-1 km/h in the evening.
t1 + t2 = 5 .4 h.
x * t1 = 12.
t1 = 12/x.
(x-1) * t2 = 12.
t2 = 12/(x-1).
t1 + t2 = 5.4.
12/x + 12/(x-1) = 5.4.
12(x-1) + 12x = 5.4x(x-1),
12x - 12 +12x = 5.4x^2 - 5.4x,
5.4x^2 - 24x - 5.4x + 12 = 0.
5.4x^2 - 29.4x + 12 = 0,
sqrt(B^2 - 4AC) = 24.6.
X = 29.4/10.8 +- 24.6/10.8 = 2.72 +- 2.28 = 5 km/h, and 0.44.
X = 5 km/h in morning. You are correct!!.
r = x-1 km/h in the evening.
t1 + t2 = 5 .4 h.
x * t1 = 12.
t1 = 12/x.
(x-1) * t2 = 12.
t2 = 12/(x-1).
t1 + t2 = 5.4.
12/x + 12/(x-1) = 5.4.
12(x-1) + 12x = 5.4x(x-1),
12x - 12 +12x = 5.4x^2 - 5.4x,
5.4x^2 - 24x - 5.4x + 12 = 0.
5.4x^2 - 29.4x + 12 = 0,
sqrt(B^2 - 4AC) = 24.6.
X = 29.4/10.8 +- 24.6/10.8 = 2.72 +- 2.28 = 5 km/h, and 0.44.
X = 5 km/h in morning. You are correct!!.
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