If your bank offered you 3% interest on $5,000 in your savings account, how much money would you have in your account at the end
1 answer:
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Answer:
the length of the rectangle is, 21 in.
Step-by-step explanation:
Area of the rectangle(A) is given by:
.....[1]
where,
l is the length of the rectangle
w is the width of the rectangle.
As per the statement:
The width of a rectangle is 9 in. shorter than its length.
⇒
It is also given that:
The area of the rectangle is 252 in².
⇒A = 252 in².
Substitute in [1] we have;
⇒
⇒
Factorize this equation:
Split the middle term;
⇒
⇒
⇒
By zero product property we have;
and
⇒ and
Since, length cannot be in negative
⇒
Therefore, the length of the rectangle is, 21 inches.
Answer:
The half-life of the radioactive substance is of 3.25 days.
Step-by-step explanation:
The amount of radioactive substance is proportional to the number of counts per minute:
This means that the amount is given by the following differential equation:
In which k is the decay rate.
The solution is:
In which Q(0) is the initial amount:
8000 counts per minute on a Geiger counter at a certain time
This means that
500 counts per minute 13 days later.
This means that . We use this to find k.
So
Determine the half-life of the radioactive substance.
This is t for which Q(t) = 0.5Q(0). So
The half-life of the radioactive substance is of 3.25 days.