Question
Table below shows the frequency $f$ with which $'x'$ alpha particles radiated from a diskette:
Calculate the mean and variance.
| $x$ | $0$ | $1$ | $2$ | $3$ | $4$ | $5$ | $6$ | $7$ | $8$ | $9$ | $10$ | $11$ | $12$ |
| $f$ | $51$ | $203$ | $383$ | $525$ | $532$ | $408$ | $273$ | $139$ | $43$ | $27$ | $10$ | $4$ | $2$ |