An expression is shown 12.395 - (2.24 • 3.9) what is the value of the expression

18. Manufacturers often package products in a way that uses the least amount of material One measure of the efficiency of a pack

Lemur [1.5K]

Answer:

a. $E=\frac{2h+2r}{rh}$

b.

E of first can = $E=\frac{2h+2r}{rh}$

E of second can = $E=\frac{h+2r}{rh}$

c. Yes

Step-by-step explanation:

The efficiency ratio is:

E = Surface Area / Volume

a.

We can write:

$E=\frac{S}{V}$

Where

S is surface area of cylinder

V is volume of cylinder

The formulas are:

S = $2\pi rh+2\pi r^2$

V = $\pi r ^2 h$

So, the <u>efficiency ratio (E) </u>is:

$E=\frac{2\pi rh+2\pi r^2}{\pi r^2 h}\\E=\frac{\pi r(2h+2r)}{\pi r(rh)}\\E=\frac{2h+2r}{rh}$

b.

The first can has radius "r" and height "h", so the efficiency ratio is:

$E=\frac{S}{V}\\E=\frac{2\pi rh+2\pi r^2}{\pi r^2 h}\\E=\frac{\pi r(2h+2r)}{\pi r(rh)}\\E=\frac{2h+2r}{rh}$

The second can has same height, "h", and twice radius, "2r", so the efficiency ratio becomes:

$E=\frac{S}{V}\\E=\frac{2\pi (2r)h+2\pi (2r)^2}{\pi (2r)^2 h}\\E=\frac{4\pi rh +8\pi r^2}{4\pi r^2h}\\E=\frac{4\pi r(h+2r)}{4\pi r(rh)}\\E=\frac{h+2r}{rh}$

c.

We now need to say if the company made a good decision or not.

If you look at both the Efficiency ratios above, you will see that the difference is in the numerator.

The first can has "2h"

The second can has "h"

The "2h" makes the numerator for the first can BIGGER than the "h" of the second can, so the Efficiency ratio of first can is thus, BIGGER.

We need smaller ratio.

So, 2nd can has indeed smaller ratio, so the company made a good decision.

6 0

2 years ago

A motor scooter travels 20 mi in the same time that a bicycle covers 8

melamori03 [73]

The scooter is 20 miles per hour and the bicycle is 8 miles per hour. Because twice the rate of the bicycle is sixteen miles then the scooter minus 16 is four as in the four miles per hour mentioned above, so its only one hour then we divide 20 and 8 both seperatly by one and those are your answers

6 0

1 year ago

Which must be true if t + u/ t = 12/11 ?

SpyIntel [72]

Sorry, I don't know how to solve this equation.

Please visit the examples page to see what the calculator currently supports.

8 0

2 years ago

Draw a bar model that shows how the number of hours in March compares with the number of hours in February of this year.

gogolik [260]

Okay so first we need to find how many days are in March and February. March has 31 days and because this year was a leap year February has 29 days.

The next step is to convert days to hours.
March: 31x24=744
February: 29x24=696

Now its time to graph

8 0

2 years ago

Read 2 more answers

You plan to accumulate 100,000 at the end of 42 years by making the follow-

Mariana [72]

Answer:

Y = 479.17

Step-by-step explanation:

At the end of year 14, the balance from the deposits of X can be found using the annuity due formula:

A = P(1+r/n)((1 +r/n)^(nt) -1)/(r/n)

where P is the periodic payment, n is the number of payments and compoundings per year, t is the number of years, and r is the annual interest rate.

A = X(1.07)(1.07^14 -1)/0.07 ≈ 24.129022X

This accumulated amount continues to earn interest for the next 28 years, so will further be multiplied by 1.07^28. Then the final balance due to deposits of X will be ...

Ax = (24.129022X)(1.07^28) = 160.429967X

__

The same annuity due formula can be used for the deposits of Y for the last 10 years of the interval:

Ay = Y(1.07)(1.07^10 -1)/.07 = 14.783599Y

__

Now we can write the two equations in the two unknowns:

Ax +Ay = 100,000

X - Y = 100

From the latter, we have ...

X = Y +100

So the first equation becomes ...

160.429967(Y +100) +14.783599Y = 100000

175.213566Y +16,043.00 = 100,000

Y = (100,000 -16,043)/175.213566 ≈ 479.17

Y is 479.17

7 0

1 year ago