Question

Pls helppp anyoneeee plssss

Answer 1

Given:

Mean = 45

Standard deviation = 9

Confidence level = 95%.

To find:

The confidence interval.

Solution:

The formula for confidence interval is:

$C.I.=\overline{x}\pm z\dfrac{\sigma}{\sqrt{n}}$

Where, $\overline{x}$ is mean, z is the z-value at given level of confidence, $\sigma$ is the standard deviation and n is the number of observations.

The z-value at 95% confidence level is 1.96.

Here number of observations are not given. Assume it is 1.

Putting $\overline{x}=45,\sigma=9,z=1.96,n=1$.

$C.I.=45\pm 1.96\dfrac{9}{\sqrt{1}}$

$C.I.=45\pm 1.96(9)$

$C.I.=45\pm 17.64$

It can be written as

$C.I.=[45-17.64,45+17.64]$

$C.I.=[27.36,62.64]$

Approximate the value to the nearest whole number.

$C.I.=[27,63]$

The interval for the middle 95% of snowfall is  27 to 63.

Therefore, the correct option is A.