The answer would be A. because 30 is how many she did but then h is the variable we are trying to figure out like the h can be any letter it just is there to show that the "person" does not know what the number is. Hope this helped!
The answer to this question would be A
Generic exponential growth model: y = Ao[1+r]^t
In this case: r = 3.5% = 0.035
y = 2Ao .....[the double of the initial value]
Then: 2Ao =Ao (1 + 0.035)^t
(1.035)^t =2
Take logarithm to both sides
t ln(1.035) = ln(2)
t = ln(2) / ln(1.035) = 0.693 / 0.0344 = 20.15
Answer: 20.15 hours.
Z=11 is the answer for this problem
