Assume the readings on thermometers are normally distributed with a mean of 0degreesC and a standard deviation of 1.00degreesC. Find the probability that a randomly selected thermometer reads between negative 2.06 and negative 1.43 and draw a sketch of the region.

Respuesta :

Answer:

[tex]P(-2.06<X<-1.43)=P(\frac{-2.06-\mu}{\sigma}<\frac{X-\mu}{\sigma}<\frac{-1.43-\mu}{\sigma})=P(\frac{-2.06-0}{1}<Z<\frac{-1.43-0}{1})=P(-2.06<z<-1.43)[/tex]

And we can find this probability with this difference:

[tex]P(-2.06<z<-1.43)=P(z<-1.43)-P(z<-2.06)= 0.0765 -0.0197=0.0567 [/tex]

Step-by-step explanation:

Previous concepts

Normal distribution, is a "probability distribution that is symmetric about the mean, showing that data near the mean are more frequent in occurrence than data far from the mean".

The Z-score is "a numerical measurement used in statistics of a value's relationship to the mean (average) of a group of values, measured in terms of standard deviations from the mean".  

Solution to the problem

Let X the random variable that represent the temperatures of a population, and for this case we know the distribution for X is given by:

[tex]X \sim N(0,1)[/tex]  

Where [tex]\mu=0[/tex] and [tex]\sigma=1[/tex]

We are interested on this probability

[tex]P(-2.06<X<-1.43)[/tex]

And the best way to solve this problem is using the normal standard distribution and the z score given by:

[tex]z=\frac{x-\mu}{\sigma}[/tex]

If we apply this formula to our probability we got this:

[tex]P(-2.06<X<-1.43)=P(\frac{-2.06-\mu}{\sigma}<\frac{X-\mu}{\sigma}<\frac{-1.43-\mu}{\sigma})=P(\frac{-2.06-0}{1}<Z<\frac{-1.43-0}{1})=P(-2.06<z<-1.43)[/tex]

And we can find this probability with this difference:

[tex]P(-2.06<z<-1.43)=P(z<-1.43)-P(z<-2.06)= 0.0765 -0.0197=0.0567 [/tex]