Answer:
Son
Explanation:
Just got 100%, but further explanation: Es and esta are both easy to rule out, as neither of them refers to "they" (Alan y Enrique), and estan does not work because of the weird rules. Tbh I feel like you just have to memorize them except in some cases where one just clearly makes more sense than the other.
you need to have 120 college credits to earn a bachelor's degree.
that is equivalent to 40 classes since each class is 3 points.!
Hope I helped!
Yes. This is very needed to be successful in life. Everyone go get a smelly whiff of Dora...! :)
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Answer:</h3>
60 days
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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.
Fractions
Another way to solve this is to use fractions.
- 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.