Question

question 1 - 13
a medicine ball is filled with sand and has a radius of 1.5 feet. sand weighs 3.5 pounds per cubic foot. what is the total weight of the medicine ball to the nearest whole number?
14 pounds
42 pounds
7 pounds
81 pounds

Explanation:

Step1: Calculate volume of the ball

The ball is spherical. The volume formula for a sphere is $V = \frac{4}{3}\pi r^{3}$, where $r = 1.5$ feet. So $V=\frac{4}{3}\pi(1.5)^{3}=\frac{4}{3}\pi\times3.375 = 4.5\pi$ cubic - feet.

Step2: Calculate the total weight

The sand weighs 3.5 pounds per cubic - foot. So the total weight $W$ is the product of the volume and the weight per cubic - foot. $W=3.5\times V=3.5\times4.5\pi$.
$W = 3.5\times4.5\pi=15.75\pi\approx15.75\times3.14 = 49.455\approx49$ pounds.

Answer:

49 pounds