An element with a mass of 990 grams decays by 16.9% per minute. To the nearest
1 answer:
Answer:
It will take 13.58 minutes until there are 80 grams of the element remaining
Step-by-step explanation:
An element with a mass of 990 grams decays by 16.9% per minute.
We are supposed to find how long will it be until there are 80 grams of the element remaining
Formula :
N(t)=Amount after t minutes
=Initial amount
r = rate of decrease = 0.169
t = time in minutes
Substitute the values in the formula :
t=13.58
Hence It will take 13.58 minutes until there are 80 grams of the element remaining
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Answer:
And rounded up we have that n=385
Step-by-step explanation:
Previous concepts
A confidence interval is "a range of values that’s likely to include a population value with a certain degree of confidence. It is often expressed a % whereby a population means lies between an upper and lower interval".
The margin of error is the range of values below and above the sample statistic in a confidence interval.
Normal distribution, is a "probability distribution that is symmetric about the mean, showing that data near the mean are more frequent in occurrence than data far from the mean".
Solution to the problem
In order to find the critical value we need to take in count that we are finding the interval for a proportion, so on this case we need to use the z distribution. Since our interval is at 99% of confidence, our significance level would be given by and
. And the critical value would be given by:
The margin of error for the proportion interval is given by this formula:
(a)
And on this case we have that and we are interested in order to find the value of n, if we solve n from equation (a) we got:
(b)
We can use as an estimator for p . And replacing into equation (b) the values from part a we got:
And rounded up we have that n=385