Answer:
The function that represents the mass of the sample after t days is
.
The percentage rate of change per hour is of -2.46%.
Step-by-step explanation:
Exponential amount of decay:
The exponential amount of decay for an amount of a substance after t days is given by:

In which A(0) is the initial amount, and r is the decay rate, as a decimal.
Element X is a radioactive isotope such that its mass decreases by 59% every day. The experiments starts out with 390 grams of Element X.
This means, respectively, that 
So



The function that represents the mass of the sample after t days is
.
Hourly rate of change:
Decreases by 59% every day, which means that for 24 hours, the rate of change is of -59%. So
-59%/24 = -2.46%
The percentage rate of change per hour is of -2.46%.
Answer:
$70,201.38
Step-by-step explanation:
To determine the principal amount, we can use the formula:

A = $200,000
r = 7% or 0.07
t = 15 years
n = 12
Now let's substitute our values.



So the principal needed to get 200,000 in 15 years is $70,201.38.
Answer:
1.66666666667
Step-by-step explanation:
Given that 24 hours is one full day, we can deduce that 2400 hours is 100 days. One full cycle from that time is equivalent to that time therefore, 2400 hours after 5pm is 5pm.