Answer:
Her speed on the summit was 35 mph.
Step-by-step explanation:
Her speed on the summit was "x" mph while her speed while climbing was "x - 10" mph. The distance she rode uphill was 55 miles and on the summit it was 28 miles. The total time she explored the mountain was 3 hours. Therefore:
time uphill = distance uphill / speed uphill = 55 / (x - 10)
time summit = distance summit / speed summit = 28 / x
total time = time uphill + time summit
3 = [55 / (x - 10)] + 28 / x
3 = [55*x + 28*(x - 10)]/[x*(x - 10)]
3*x*(x - 10) = 55*x + 28*x - 280
3x² - 30*x = 83*x - 280
3x² - 113*x + 280 = 0
x1 = {-(-113) + sqrt[(-113)² - 4*(3)*(280)]}/(2*3) = 35 mph
x2 = {-(-113) - sqrt[(-113)² - 4*(3)*(280)]}/(2*3) = 2.67 mph
Since her speed on the uphill couldn't be negative the speed on the summit can only be 35 mph.
Answer:
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It is 800 because the 4 can not tell the what to do so that it is
Answer:
I think its 1200 not sure though
Answer:
6400
Step-by-step explanation:
Given the profit function ;
P(c) = –20c2 + 320c + 5,120
The maximum value is given by :
f(h) ; where, h = - b /2a
From P(C) ; a = - 20 ; b = 320
h = - b / 2a = - 320 / 2(-20) = - 320 / 40 = 8
c = h
P(8) = –20(8)² + 320(8) + 5,120
P(8) = - 1280 + 2560 + 5120
= 6400
