Respuesta :
Answer:
[tex] P(38.6 <X <57.8)[/tex]
And we can assume a normal distribution and then we can solve the problem with the z score formula given by:
[tex]z=\frac{X -\mu}{\sigma}[/tex]
And replacing we got:
[tex] z=\frac{38.6- 45}{16}= -0.4[/tex]
[tex] z=\frac{57.8- 45}{16}= 0.8[/tex]
We can find the probability of interest using the normal standard table and with the following difference:
[tex] P(-0.4 <z<0.8)= P(z<0.8) -P(z<-0.4) = 0.788-0.345= 0.443[/tex]
Step-by-step explanation:
Let X the random variable who represent the expense and we assume the following parameters:
[tex]\mu = 45, \sigma 16[/tex]
And for this case we want to find the percent of his expense between 38.6 and 57.8 so we want this probability:
[tex] P(38.6 <X <57.8)[/tex]
And we can assume a normal distribution and then we can solve the problem with the z score formula given by:
[tex]z=\frac{X -\mu}{\sigma}[/tex]
And replacing we got:
[tex] z=\frac{38.6- 45}{16}= -0.4[/tex]
[tex] z=\frac{57.8- 45}{16}= 0.8[/tex]
We can find the probability of interest using the normal standard table and with the following difference:
[tex] P(-0.4 <z<0.8)= P(z<0.8) -P(z<-0.4) = 0.788-0.345= 0.443[/tex]
