The volume $V$ of a sphere of radius $r$ is given by $V=\frac43\pi r^3$. For a sphere of volume $V=100\text{ cm}^3$, which of the following is closest to the radius?
A bag contains red and yellow balls such that the ratio red : yellow is $5:7$. Then 10 balls of each colour are removed and the ratio changes to $5:8$. How many balls were originally in the bag?
In the solution to this number puzzle, whenever there are three numbers in a straight line, the middle number is the sum of the other two. What is the value of $x$?
The hypotenuse of a right-angled triangle has length $6\text{ cm}$. The perimeter of the triangle is $14\text{ cm}$. What is the area of the triangle in square centimetres?
I have two identical dice, each with faces $1,\frac12,\sqrt3,\frac1{\sqrt3},\frac1{\sqrt2}$ and $\frac{\sqrt3}{2}$. I roll both dice and multiply the two numbers rolled, then simplify my answer. What is the probability that this product is rational?
A $15\text{ cm}\times20\text{ cm}$ rectangle is cut into two triangles. One triangle is rotated and placed on top of the other triangle as shown to form a concave pentagon. What is the perimeter of the pentagon?