Hello!
A sample of Bromine-82 begins at 80 mL. We are given that this value will decrease by half of its current amount every 35 hours. First, we'll determine the number of times that 35 goes into 140. This will reveal the number of times we should divide the sample by 2:
140 ÷ 35 = 4
We have now proven that there are 4 periods of 35 hours in 140 hours. This means that we will divide the sample in half a total of 4 times, as follows:
1. 80 ÷ 2 = 40
2. 40 ÷ 2 = 20
3. 20 ÷ 2 = 10
4. 10 ÷ 2 = 5
We have now proven that an 80 mL sample of Bromine-82 will be reduced to only 5 mL after 140 hours. Therefore, the correct answer is 5 mL.
I hope this helps!
Answer:
27
Step-by-step explanation:
15x-31 = 9x+11
6x-31 = 11
6x = 42
x = 7
15x -31 + 9x + 11 + s = 180
15(7) -31 + 9(7) + 11 + s = 180
105 - 31 + 63 + 11 + s = 180
153 + s = 180
s = 27
The <em><u>correct answer</u></em> is:
c)75.4 to 94.6
Explanation:
The formula for a confidence interval is:
,
where μ is the mean, z is the z-score associated with the level of confidence we want, σ is the standard deviation, and n is the sample size.
Our mean is 85, our standard deviation is 12, our sample size is 6, and since we want 95% confidence, our z-score is 1.96:
