Astrology is pseudoscience. What can you conclude about the claims made by astrology?
1 answer:
You might be interested in
<h3>Answer:</h3>
60 days
<h3>Explanation:</h3>Half-life is the amount of time it takes half of a substance to decay away.
Guess and Check
One method for solving half-life problems like this is to guess and check. To do this, we can continue to divide 475mg by 2 until we get to 30mg.
- 475 ÷ 2 = 237.5
- 237.5 ÷ 2 = 118.75
- 118.75 ÷ 2 = 59.375
- 59.375 ÷ 2 = 29.6875
As seen here, it takes approximately 4 half-lives for this sample of Ra-225 to decay to 30mg. Now, we can multiply 4 by the length of the half-life, 15 days.
- 4 * 15 = 60 days.
Fractions
Another way to solve this is to use fractions.
- 30 is about 1/16 of 475
- 16 is equivalent to
.
This means that it takes 4 half-lives for 475mg to decay to 30mg. Using the same method above, we can tell that 4 half-lives are 60 days.
Important Note
In this question, I rounded occasionally. So, not all of the values are exact, but they are all very close.
Inequalities are used to represent unequal expressions.
The solution set to is:
The inequality is given as:
From the inequality above, we have the following observation.
- The value of variable x starts from 7/16 (inclusive)
- The value of variable x has no end (i.e. infinity)
Because, 7/16 is inclusive of the values of x, we make use of the open square bracket i.e. [
We treat , as an exclusive value. So, we make use of the close parenthesis i.e. )
Hence, the solution set is:
Read more about inequalities at: