91Ó°ÊÓ

We are given that sample has $21$people.

Mean $\overline{x}=52.5$

Standard deviation $s=6.5$

According to Chebyshev's Rule,

$$\begin{gathered} \overline{x}=52.5 \\ \overline{x}-s=52.5-6.5=46.0 \\ \overline{x}-2s=52.5-2×6.5=39.5 \\ \overline{x}-3s=52.5-3×6.5=33.0 \\ \overline{x}+s=52.5+6.5=59.0 \\ \overline{x}+2s=52.5+2×6.5=65.5 \\ \overline{x}+3s=52.5+3×6.5=72.0 \end{gathered}$$

Required graph is

We are given that sample has $21$people.

Mean $\overline{x}=52.5$

Standard deviation $s=6.5$

According to Chebyshev's rule ,if

$k=2$, then at least $75\%$of the people in the sample have early onset dementia within two standard deviations to either side of the mean.

Now,

$21×0.75≈16$

Now, two standard deviations to either side of the mean is from

$39.5$to $65.5$years.

Interpretation- At least $16$out of $21$people in the sample are with early-onset dementia between $39.5$and $65.5$years

We are given that sample has $21$people.

Mean $\overline{x}=52.5$

Standard deviation $s=6.5$

According to Chebyshev's rule ,if

$k=3$, then at least $89\%$of the people in the sample are with early onset dementia within two standard deviations to either side of the mean.

Now,

$21×0.89≈19$

Now, two standard deviations to either side of the mean is from

$33$to $72$years.

Interpretation At least $19$out of $21$people in the sample are with early-onset dementia between $33$and $72$years