9514 1404 393
Answer:
A. 64 miles per hour
Step-by-step explanation:
In a linear equation, the "unit rate" is generally the coefficient of the variable. The units of the unit rate depend on the definition of the relationship.
Here, the time t is in hours, so the "unit rate" will be <something> per hour. The answer choices suggest that the <something> is "miles". That is, the units of the equation are ...
(miles/hour) × (hours) = miles
With numbers/variables, that is ...
(64 miles/hour) × (t hours) = 384 miles
The unit rate is 64 miles per hour.
Answer:
Step-by-step explanation:
a . possible
b. ehhh
c. possible
d. possible
choose one
The man travelled in different ways: by rail, by taxi, by ___ and by foot. I placed a blank there because there seems to be a missing word in the given problem above. For sample purposes, let's just assume that is travel by bus.
Since all of these travels are equal to 1 whole journey, you can express each travel as a fraction. When you add them up, the answer would be 1. So,
3/8 + 1/4 + 1/8 + x = 1
The variable x here denotes the fraction of his travel by foot. We are only given the exact distance travelled on foot which is 2 km. We have to find the fraction of the travel by foot to determine the length of the total distance travelled. Solving for x,
x = 1 - 3/8 - 1/4 - 1/8
x = 1/4
That means that the travel by foot comprises 1/4 of the whole journey. Thus,
Let total distance be D.
1.4*D = 2 km
D = 8 km
Therefore, the man travelled a total of 8 kilometers.
Answer:
The dimensions that minimize the cost of materials for the cylinders have radii of about 3.628 cm and heights of about 7.256 cm.
Step-by-step explanation:
A cylindrical can holds 300 cubic centimeters, and we want to find the dimensions that minimize the cost for materials: that is, the dimensions that minimize the surface area.
Recall that the volume for a cylinder is given by:
Substitute:
Solve for <em>h: </em>
Recall that the surface area of a cylinder is given by:
We want to minimize this equation. To do so, we can find its critical points, since extrema (minima and maxima) occur at critical points.
First, substitute for <em>h</em>.
Find its derivative:
Solve for its zero(s):
![\displaystyle \begin{aligned} (0) &= 4\pi r - \frac{600}{r^2} \\ \\ 4\pi r - \frac{600}{r^2} &= 0 \\ \\ 4\pi r^3 - 600 &= 0 \\ \\ \pi r^3 &= 150 \\ \\ r &= \sqrt[3]{\frac{150}{\pi}} \approx 3.628\text{ cm}\end{aligned}](https://tex.z-dn.net/?f=%5Cdisplaystyle%20%5Cbegin%7Baligned%7D%20%280%29%20%26%3D%204%5Cpi%20r%20%20-%20%5Cfrac%7B600%7D%7Br%5E2%7D%20%5C%5C%20%5C%5C%204%5Cpi%20r%20-%20%5Cfrac%7B600%7D%7Br%5E2%7D%20%26%3D%200%20%5C%5C%20%5C%5C%204%5Cpi%20r%5E3%20-%20600%20%26%3D%200%20%5C%5C%20%5C%5C%20%5Cpi%20r%5E3%20%26%3D%20150%20%5C%5C%20%5C%5C%20r%20%26%3D%20%5Csqrt%5B3%5D%7B%5Cfrac%7B150%7D%7B%5Cpi%7D%7D%20%5Capprox%203.628%5Ctext%7B%20cm%7D%5Cend%7Baligned%7D)
Hence, the radius that minimizes the surface area will be about 3.628 centimeters.
Then the height will be:
![\displaystyle \begin{aligned} h&= \frac{300}{\pi\left( \sqrt[3]{\dfrac{150}{\pi}}\right)^2} \\ \\ &= \frac{60}{\pi \sqrt[3]{\dfrac{180}{\pi^2}}}\approx 7.25 6\text{ cm} \end{aligned}](https://tex.z-dn.net/?f=%5Cdisplaystyle%20%20%5Cbegin%7Baligned%7D%20h%26%3D%20%5Cfrac%7B300%7D%7B%5Cpi%5Cleft%28%20%5Csqrt%5B3%5D%7B%5Cdfrac%7B150%7D%7B%5Cpi%7D%7D%5Cright%29%5E2%7D%20%20%5C%5C%20%5C%5C%20%26%3D%20%5Cfrac%7B60%7D%7B%5Cpi%20%5Csqrt%5B3%5D%7B%5Cdfrac%7B180%7D%7B%5Cpi%5E2%7D%7D%7D%5Capprox%207.25%206%5Ctext%7B%20cm%7D%20%20%20%5Cend%7Baligned%7D)
In conclusion, the dimensions that minimize the cost of materials for the cylinders have radii of about 3.628 cm and heights of about 7.256 cm.
