The percentage of the radioactive isotope left is 25.0000%.
<h3>What is the half life?</h3>
The half life of a radioactive isotope is the time that will elapse before only half of the number of original isotopes will remain.
Now;
We are told that;
Half life (t1/2) = 55 days
Time taken (t) = 115 days
Ratio of isotope remaining = N/No
Thus;
N/No = (1/2)^t/t1/2
N/No = (1/2)^115/55
N/No = (1/2)^2
N/No =1/4
Hence, the percentage = 1/4 * 100/1 = 25.0000%
Learn more about half life of an isotope:brainly.com/question/16387602
#SPJ1
Answer:
B. 840
Step-by-step explanation:
21 is 70% of 30 and 70% of 1,200 is 840.
Answer:
-7
Step-by-step explanation:
To find y, follow these steps:
4y - 2 (1 - y) = -44
First, distribute the -2 into the parenthesis:
4y - 2 + 2y = -44
The reason the 2y is positive is due to the fact that negative and negative cancel each other out and form a positive.
Now, combine like terms:
6y - 2 = -44
To get y, you need to isolate it from the constants. In order to do so, do the inverse relationship for the constant -2. To do this, add 2 to -44:
6y = -42
Now, divide six on both sides. You divide because six is currently being multiplied with y. Keep in mind that the 42 is still negative!
y = -7
Hope this helps!
