# Math Help - volumes of cylinders

1. ## volumes of cylinders

a right circular cylinder has a diameter of 5.7 inches and a height of 6.4 feet
a.) what is the volume of the cylinder in ft^3?
b.) what is the volume of the cylinder in cubic metres?
c.)what is the volume of the cylinder in litres?

so for ft^3 i knew that
the volume of a cylinder is (pi)r^2*h
so i did 2.85in.^2 * 6.4ft
v= 51.984 ft^3 is this correct?
and how do i do the other ones?^

2. ## volume of cylinders

Hi gabriel,
You have the right formula but units must be consistent. R must be converted to feet and volume will then be in cubic ft . So what must you do to get results in cubic meters or in liters.You also can use the diameter directly by using a revised formula. pi d^2 /4 for area. Look up conversion factors.

bjh

3. so is the answer 1.134 cubic inches?
i found out that r=2.85 in so r=.2375 feet
so (pi)(2.375ft)^2(6.4 feet)
v=1.134 ft^3
^correct?

4. Hi again gabriel,
Your answer to question 1 is correct but you made a decimal error in your calculation. How about doing 2 and 3?

bjh

5. ok so for 2 i got 0.1054 m^3
and for 3 i got 7.19 x 10^-3 litres
1 liter= 0.03531 ft ^3

6. Hi gabriel,

If you showed your work I could tell you where you went wrong. Both answers for questions for 2 and 3 are wrong. 1 liter is 0.03531 cu ft as you show so the reciprocal equals = 28.32 which is the number of liters in a cu ft

bjh