cal_a10_openqa2

course MTh 173

Question: `q query problem 1.6.9 (was 1.10.16)cubic polynomial representing graph. What cubic polynomial did you use to represent the graph?

YYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYY

Your solution:

Zeroes are at x = -2, 1, 5

Y = k(x+2)(x-1)(x-5)

When x is 0, y =2

2 = k(0+2)(0-1)(0-5)

2 = k(10) = 0.2

Y = 0.2(x+2)(x-1)(x-5)

confidence rating: 3

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Given Solution:

*&*& The given function has zeros at x = -2, 1, 5, so y = k (x+2)(x-1)(x-5).

At x = 0 the function has value 2, so 2 = k (0+2)(0-1)(0-5), or 2 = 10 k.

Thus k = .2 and the function is

y = .2 ( x+2)(x-1)(x-5). **

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Self-critique (if necessary): ok

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Self-critique Rating: ok

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Question: `q Query problem 1.6.15 (formerly 1.4.19) s = .01 w^.25 h^.75what is the surface area of a 65 kg person 160 cm tall?

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Your solution:

0.01w^0.25h^0.75

0.01(65^0.25)(160^0.75) = 1.278m^2

confidence rating: 3

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Given Solution:

** Substituting we get

s = .01 *65^.25 *160^.75 = 1.277meters^2 **

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Self-critique (if necessary): ok

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Self-critique Rating: ok

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Question: `q What is the weight of a person 180 cm tall whose surface area is 1.5 m^2?

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Your solution:

S = 0.01w^0.25(h^0.75)

1.5 = 0.01w^0.25(180^0.75)

1.5 = 0.01w^0.25(49.14)

0.0305= 0.01w^0.25

3.052=w^0.25

w = 86.805

confidence rating:

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Given Solution:

** Substituting the values we get

1.5 = .01 w^.25*180^.75 . Dividing both sides by 180:

1.5/180^.75

.01w^.25. Dividing both sides by .01:

3.05237 = w^.25 Taking the fourth power of both sides:

w = 3.052^4 = 86.806 **

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Self-critique (if necessary): ok

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Self-critique Rating: ok

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Question: `q For 70 kg persons what is h as a function of s?

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Your solution:

S = 0.01w^0.25h^0.75

S = 0.0289 h^0.75

H^0.75 = s / 0.0289

H^0.75 = 34.60s

H = 113s^4/3

I got 113 by rounding to 3 sig figs. The given solution was 111

confidence rating: 3

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Given Solution:

** Substituting 70 for the weight we get

s = .01 *70^.25 h^.75

s = .02893 h^.75

s/.02893 = h^.75

34.60 s = h^.75

Taking the 1/.75 = 4/3 power of both sides:

(34.60 s)^(4/3) = h

h = 111 s^(4/3), approximately **

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Self-critique (if necessary): ok

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Self-critique Rating: ok

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