If the rate of the boat in still water is 20 mph, and the rate of the current is x mph, what is the rate of the boat going upstr
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Answer:
According to the rule of 72, the doubling time for this interest rate is 8 years.
The exact doubling time of this amount is 8.04 years.
Step-by-step explanation:
Sometimes, the compound interest formula is quite complex to be solved, so the result can be estimated by the rule of 72.
By the rule of 72, we have that the doubling time D is given by:
The interest rate is in %.
In our exercise, the interest rate is 9%. So, by the rule of 72:
.
According to the rule of 72, the doubling time for this interest rate is 8 years.
Exact answer:
The exact answer is going to be found using the compound interest formula.
In which A is the amount of money, P is the principal(the initial sum of money), r is the interest rate(as a decimal value), n is the number of times that interest is compounded per unit t and t is the time the money is invested or borrowed for.
So, for this exercise, we have:
We want to find the doubling time, that is, the time in which the amount is double the initial amount, double the principal.
is double the initial amount, double the principal.
The interest is compounded anually, so
Now, we apply the following log propriety:
So:
The exact doubling time of this amount is 8.04 years.
The Volume of cylinder is 3770 cubic millimeters
But, the correct option is not available in options given.
Step-by-step explanation:
Height of cylinder = 3mm
Diameter of cylinder = 40mm
Volume of cylinder = ?
The formula used to find Volume of cylinder is:
Putting values in the formula:
Since we need radius,
radius = diameter/2
radius = 40/2
radius = 20 mm
So,
The Volume of cylinder is 3770 cubic millimeters
But, the correct option is not available in options given.
Keywords: Volume of cylinder
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