We have $2$ rectangular sheets of paper, $M$ and $N$, of dimensions $6$ cm $\times$ $1$ cm each. Sheet $M$ is rolled to form an open cylinder by bringing the short edges of the sheet together. Sheet $N$ is cut into equal square patches and assembled to form the largest possible closed cube. ... to that of the cube is _____________ $\frac{\pi}{2}\\$ $\frac{3}{\pi} \\$ $\frac{9}{\pi} \\$ $3 \pi$

There are five bags each containing identical sets of ten distinct chocolates. One chocolate is picked from each bag. The probability that at least two chocolates are identical is _________ $0.3024$ $0.4235$ $0.6976$ $0.8125$

A polygon is convex if, for every pair of points, $P$ and $Q$ belonging to the polygon, the line segment $PQ$ lies completely inside or on the polygon. Which one of the following is $\underline {\text{NOT}}$ a convex polygon?