All categories

3 years ago

Find the approximate radius of a sphere with a surface area of 400 square inches.

1 answer:

7 0

The equation for surface area of a sphere is SA=4*pi*r^2
We can plug in what we know to solve for r
400=4*pi*r^2
100=pi*r^2 (divide out the 4)
100/pi=r^2 (divide out the pi)
√(100/pi)=r (square root of both sides)
r=5.6 rounded to the nearest tenth

You might be interested in

Previously, an organization reported that teenagers spent 24.5 hours per week, on average, on the phone. The organization thinks

Lena [83]

Answer:

We need to develop a one-tail t-student test ( test to the right )

We reject H₀ we find evidence that student spent more than 24,5 hours on the phone

Step-by-step explanation:

Sample size n = 15 n < 30

And we were asked if the mean is higher than, therefore is a one-tail t-student test ( test to the right )

Population mean μ₀ = 24,5

Sample mean μ = 25,7

Sample standard deviation s = 2

Hypothesis Test:

Null Hypothesis H₀ μ = μ₀

Alternative Hypothesis Hₐ μ > μ₀

t (c) = ?

We will define CI = 95 % then α = 5 % α = 0,05 α/2 = 0,025

n = 15 then degree of freedom df = 14

From t-student table we get: t(c) = 2,1448

And t(s)

t(s) = ( μ - μ₀ ) / s/√n

t(s) = (25,7 - 24,5) /2/√15

t(s) = 2,3237

Now we compare t(c) and t(s)

t(c) = 2,1448 t(s) = 2,3237

t(s) > t(c)

Then we are in the rejection region we reject H₀ we have evidence at 95% of CI that students spend more than 24,5 hours per week on the phone

8 0

3 years ago

Mark has 17 coins that are dimes and quarters. The total value of the coins is $2.45. How many dimes does mark have?

seropon [69]

Answer: 12 dimes and 5 quarters

Step-by-step explanation: Let's start this problem by setting up a chart so we can organize our information that we're given in this problem.

Down the left side, we'll have our different types of coins. In this case dimes and quarters. Across the top we'll have our formula which is shown below.

Number of coins · value of each coin = total value

Now let's fill out our chart.

For number of dimes and quarters, we know that mark has a total of 17 dimes and quarters but we don't know how many of each he has. In fact, that's what the problem is asking.

So if we represent our number of dimes as x, we can call our number of quarters 17 - x.

The value of each dime is 10¢ and the value of each quarter is 25¢.

Our total value based on our formula is going to come from the first column times the second column. So the total value of our dimes is x times 10 or 10x and the total value of our quarters is 17 - x times 25 or 25 (17 - x).

Our goal in this problem will be to find x because x represents our number of dimes and the problem asks how many dimes does he have. If we know the number of dimes, we can easily find the number of dimes and we'll have our answer. However, we need an equation in order to find x.

It's important to understand that he information in this equation will always come from the last column of your chart, the total value column. So what do we know about the total value of our dimes and the total value of our quarters?

Well we know that the total value of all of our coins is $2.45. So if we add the total value of our dimes + the total value of our quarters, that should equal $2.45. So below the chart I added an additional box and I put 245 in it. Notice that I wrote 245 in terms of cents because our value of dimes and value of quarters is also written in terms of cents and we need to be constient.

So here's our equation.

10x + 25 (17 - x) = 245.

If we solve this, we get x = 12.

Going back up into our chart, remember that x represents our number of dimes so Mark has 12 dimes. To get his number of quarters, we take 17 - x which is 17 - 12 or 5 quarters and that's our answer.

I have also attached the chart that I have made below.

7 0

3 years ago

What is the tens fact for 14-6

sasho [114]

14-6=8 and its 10 x1

4 0

3 years ago

PLEASE HELP THIS IS PYTHAGOREAN THEORM 3D

andreev551 [17]

Answer:

The height is 6.3

Step-by-step explanation:

Pythagorean Theorm: a² + b² = c²

5² + b² = 8²

25 + b² = 64

b² = 39

b = 6.2449979984

7 0

3 years ago

Does it matter what order you add the numbers in the problem

EastWind [94]

Answer:no it doesn’t matter what order you add the number.

Step-by-step explanation:

2 plus 3 equals 5

3 plus 2 equals 5

No matter the way you add 3 and 2, you still get 5

5 0

3 years ago