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Free_Kalibri [48]
3 years ago
9

New streetlights will be installed along a section of the highway. The posts for the streetlights will be 7.5 m tall and made of

aluminium. The city can choose to buy the posts shaped like rectangular prisms. The cylindrical posts have a hollow core, with aluminium 2.5 cm thick, and an outer diameter of 53.4 cm. The rectangular-prism posts have a hollow core, with aluminium 2.5 cm thick, and a square base that measures 40 cm on each side.
The density of aluminium is 2.7 g/cm³, and the cost of aluminium is $0.38 per kilogram.
Part A: if all posts must be the same shape, which post design will cost the town less?
Part B: How much money will be saved per streetlight post design will cost the town less?
Mathematics
1 answer:
SIZIF [17.4K]3 years ago
6 0
First, we determine the volumes of the posts may it be cylindrical in shape or rectangular prism. 

(A) cylindrical:
                         ( π(26.7/100)² - π(24.2/100)²)*(7.5) = 0.3 m³
(B) rectangular prism:
                          (40/100)²(7.5) - (35/100)²(7.5) = 0.28125 m³

Then, we calculate for the amount of substance
 (A) cylindrical:   (0.3 m³)(2700 kg/m³) = 810 kg
 (B) rectangular prism : (0.28125 m³)(2700 kg/m³) = 759.375 kg

Then, calculate for the costs
 (A) (810 kg)($0.38/kg) = $307.8
 (B) (759.375 kg)($0.38/kg) = $288.56

Thus, the answer for A is rectangular post 
B. About $19.24 can be saved. 
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You saved $300 to spend over the summer. You decide to budget $50 to spend each week.
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Answer:

<u>Part c) </u>

The Slope of the line is: m=-50 and represents the amount of money spent per week.

<u>Part d) </u>

The y-intercept is: c=300 and represents the maximum money we have that can be spend over the weeks (i.e. our maximum budget alowed).

Step-by-step explanation:

To solve this question we shall look at linear equations of the simplest form reading:

y = mx+c    Eqn(1).

where:

y: is our dependent variable that changes as a function of x

x: is our independent variable that 'controls' our equation of y

m: is the slope of the line

c: is our y-intercept assuming an x⇔y  relationship graph.

This means that as x changes so does y as a result.

<u>Given Information: </u>

Here we know that $300 is our Total budget and thus our maximum value (of money) we can spend, so with respect to Eqn (1) here:

c=300

The budget of $50 here denotes the slope of the line, thus how much money is spend per week, so with respect to Eqn (1) here:

m=50

So finally we have the following linear equation of:

y= - 50x + 300    Eqn(2).

Notice here our negative sign on the slope of the line. This is simply because as the weeks pass by, we spend money therefore our original total of $300 will be decreasing by $50 per week.

So with respect to Eqn(2), and different weeks thus various x values we have:

Week 1: x=1 we have y= -50 *1 + 300 = -50 +300 = 250 dollars.

Week 2: x=2 we have y= -50 *2 + 300 = -100 +300 = 200 dollars.

Thus having understood the above we can comment on the questions asked as follow:

<u>Part c) </u>

The Slope of the line is: m=-50 and represents the amount of money spent per week.

<u>Part d) </u>

The y-intercept is: c=300 and represents the maximum money we have that can be spend over the weeks (i.e. our maximum budget alowed).

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Answer:

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Step-by-step explanation:

154+162=316

316/2=158

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Step-by-step explanation:

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