The area of a circle is equal to the radius squared times pie, basically:

The radius is 3, so we multiply 3 times 3 times pie to get the area.
You're gonna want to plug in the following into a calculator:

After getting 28.26 from such calculator, you need to round to the tenths place. In this number, the tenths place is the 2 next to the decimal on the right. Because the number after the 2 is a 6, that means we need to simplify the answer to (28.3). When you are rounding a number, you look at the number to the right, if it is 5 or bigger, add one and remove the rest, if it is less than 5, just get rid of the rest and leave it as it is.
Answer:
A) 277 million years
Step-by-step explanation:
Here, decay of U-238 is first order reaction. (since most of the nuclear decays are first order).
so, the equation t =
× ln(
)
where, t = time from start of reaction
k = reaction constant
A(0) = initial concentration; A = present concentration.
⇒ 4.5 billion = 4500 million years =
× ln2.
Now, given 95.82% of parent U-238 isotope is left.
⇒ t =
× ln(
)
t =
× ln(
)
⇒ t ≅ 277 million years.
Answer:
15%
Step-by-step explanation:
The first step is to calculate the decrease
= 500-425
= 75
The percentage decrease can be calculated as follows
= 75/500 ×100
= 0.15×100
= 15%
Hence the percent decrease is 15%
18 x 4 = 72
(9 x 2) x 4 = 72
9 x (2 x 4) = 72
Answer:
75%
Step-by-Step Explanation:
There are two ways to go about this.
1) We can simply put it as a fraction = 60/80.
Then since a fraction sign also means division, we divide 60 by 80 = 0.75
Then to change a decimal into a percentage, we multiply by 100% = 75%
So our answer is 75%
2) We can simply it after it is put into a fraction = 60/80 = 3/4
It should be common knowledge that 3/4 is 75% depending on what grade you are in.
But there you have it, whichever way you prefer, the answer is always 75%.