Answer:
Step-by-step explanation:
If the radius, r, is given, then the area of the circle is A = πr².
If the diameter, d, is given, then the circle area is A = π(d/2)², or A = πd² / 4.
Answer:
$2
Step-by-step explanation:
To use a percent you must change it to a decimal.
8% is .08
To find 8% of 25, we use multiplication.
.08 × 25
= 2
In case you cannot use a calculator or you want to be very quick about this, or just do a simple check... you can actually reverse the number (money, amount, etc) and the percent.
25% of 8 is not bad for doing mental math. 25% is a quarter, or 1/4 of 8 which again is 2.
Answer:
Approximately 3 grams left.
Step-by-step explanation:
We will utilize the standard form of an exponential function, given by:
![f(t)=a(r)^t](https://tex.z-dn.net/?f=f%28t%29%3Da%28r%29%5Et)
In the case of half-life, our rate <em>r</em> will be 1/2. This is because 1/2 or 50% will be left after <em>t </em>half-lives.
Our initial amount <em>a </em>is 185 grams.
So, by substitution, we have:
![\displaystyle f(t)=185\big(\frac{1}{2}\big)^t](https://tex.z-dn.net/?f=%5Cdisplaystyle%20f%28t%29%3D185%5Cbig%28%5Cfrac%7B1%7D%7B2%7D%5Cbig%29%5Et)
Where <em>f(t)</em> denotes the amount of grams left after <em>t</em> half-lives.
We want to find the amount left after 6 half-lives. Therefore, <em>t </em>= 6. Then using our function, we acquire:
![\displaystyle f(6)=185\big(\frac{1}{2}\big)^6](https://tex.z-dn.net/?f=%5Cdisplaystyle%20f%286%29%3D185%5Cbig%28%5Cfrac%7B1%7D%7B2%7D%5Cbig%29%5E6)
Evaluate:
![\displaystyle f(6)=185\big(\frac{1}{64}\big)\approx2.89\approx 3](https://tex.z-dn.net/?f=%5Cdisplaystyle%20f%286%29%3D185%5Cbig%28%5Cfrac%7B1%7D%7B64%7D%5Cbig%29%5Capprox2.89%5Capprox%203)
So, after six half-lives, there will be approximately 3 grams left.
You can't get negative 1 from any equation shown in this picture. By the way, -5 +(-9) is not negative 4, it is negative 14,because according to PEMDAS( or <span>BODMAS/BIDMAS/BEDMAS )</span>, parenthesis goes first, so it's kinda like
(-9) + -5 instead.