Answer:
20ln(3)
Step-by-step explanation:
Put 15 for A and solve for t.
15 = 45e^(-.05t)
15/45 = 1/3 = e^(-.05t) . . . . divide by 45
ln(1/3) = -.05t . . . . . . . . . . . take natural logs
20ln(3) = t . . . . . . . . . . . . . . multiply by 20, simplify
It will take 20·ln(3) years for the area to decrease to 15 km^2.
58+24=82 is the correct answer to that question because you subtract 2 from 60 then add that to 6 multiplied by 4
Answer:
x = 22
Step-by-step explanation:
I interpreted your problem as:

I simplified the problem to:

I combined like terms:

I moved all x to one side and all other constants to the other:

I divided by 3/2 (1.5) on both sides to isolate x:

Hope it helps! (:
Answer:
Step-by-step explanation:
Given : A new catalyst is being investigated for use in the production of a plastic chemical. Ten batches of the chemical are produced. The mean yield of the 10 batches is 72.5% and the standard deviation is 5.8%. Assume the yields are independent and approximately normally distributed.
To find : A 99% confidence interval for the mean yield when the new catalyst is used ?
Solution :
Let X be the yield of the batches.
We have given, n=10 ,
, s=5.8%
Since the size of the sample is small.
We will use the student's t statistic to construct a 995 confidence interval.

From the t-table with 9 degree of freedom for 


The 99% confidence interval is given by,




It can be both because there are diffrent sizes