NZ Level 8 (NZC) Level 3 (NCEA) [In development]
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Variability of Samples from Distributions

Interactive practice questions

Consider a fair $8$8 sided die with faces labeled from $1$1 to $8$8.

Let $X$X be the outcome when the die is rolled.


Complete the table of values for the probability distribution for $X$X.

$x$x $1$1 $2$2 $3$3 $4$4 $5$5 $6$6 $7$7 $8$8
$P\left(X=x\right)$P(X=x) $\editable{}$ $\editable{}$ $\editable{}$ $\editable{}$ $\editable{}$ $\editable{}$ $\editable{}$ $\editable{}$

Calculate the mean of the distribution.


Calculate the standard deviation of the distribution correct to two decimal places.


The die was rolled 20 times with the following results

$8$8 $3$3 $3$3 $5$5 $4$4
$8$8 $1$1 $7$7 $6$6 $5$5
$2$2 $2$2 $3$3 $5$5 $4$4
$3$3 $8$8 $6$6 $5$5 $1$1

Calculate the sample mean of the results.


Calculate the sample standard deviation.

Round your answer to two decimal places.

Approx 9 minutes
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The random variable $X$X is uniformly distributed with a variance of $\frac{25}{12}$2512 over the interval $1\le x\le6$1x6.

$R$R is a binomial variable with $n=14$n=14 and $p=0.25$p=0.25.

Two samples, $A$A and $B$B, each of size $10$10, are taken from $R$R and tabulated below.

The normal variable $X$X has a mean of $120$120 and a standard deviation of $15$15.

Two samples, $A$A and $B$B, each of size $10$10, are taken from $X$X and tabulated below.



Make inferences from surveys and experiments: A determining estimates and confidence intervals for means, proportions, and differences, recognising the relevance of the central limit theorem B using methods such as resampling or randomisation to assess


Use statistical methods to make a formal inference

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