54 divided by 6 would be 9 meaning he takes 9 quizzes a week. If directly proportional by the end of 7 weeks he would have taken 63 quizzes
You substitute the equation and see if it works. Also, the first one that you answered is wrong.
Answer:
It would take 24 minutes for the element to decay to 50 grams
Step-by-step explanation:
The equation for the amount of the element present, after t minutes, is:

In which Q(X) decays radioactively with a half life of 12 minutes.(0) is the initial amount and r is the rate it decreases.
Half life of 12 minutes
This means that 
So








If there are 200 grams of Element X, how long, to the nearest tenth of a minute, would it take the element to decay to 50 grams?
This is t when Q(t) = 50. Q(0) = 200.








It would take 24 minutes for the element to decay to 50 grams
In order to find the median the 1st thing I would do is put the number in order
80,84,87,88,88,90,90,95,98,100
then cross them out Start with left then go the right and so on...
until you get 1 number in the middle left (Since theirs 2 numbers in the middle add them up and divide by two ) 88+90=178 178/2=89
Median = 89
Now in Order to find the mean add up all the numbers and divide by however many numbers their are
You should get 900 then divide by 10 because their were 10 numbers
So Median=89 & Mean=90