Easy -1.2 This is a straightforward recall question requiring knowledge that Po(λ) approximates to N(λ, λ) when λ is large, with mean 31 and standard deviation √31. No calculation or problem-solving is needed beyond applying a standard result.
1 A random variable has the distribution \(\mathrm { Po } ( 31 )\). Name an appropriate approximating distribution and state the mean and standard deviation of this approximating distribution.
## Question 1:
| Answer/Working | Marks | Guidance |
|---|---|---|
| Normal | B1 | |
| 31 for mean | B1 | For mean |
| $\sqrt{31}$ or 5.57 for sd | B1 [3] | Must be sd |
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1 A random variable has the distribution $\mathrm { Po } ( 31 )$. Name an appropriate approximating distribution and state the mean and standard deviation of this approximating distribution.
\hfill \mbox{\textit{CAIE S2 2010 Q1 [3]}}