In a study, 42% of adults questions reported that their health was excellent. A researcher wishes to study the health of people living close to a coal power plant. Among the 14 adults randomly selected from this area, only 3 reported that their health was excellent. Find the probability that when 14 adults are randomly selected from the full population, only 3 or fewer report having excellent health.

Respuesta :

Answer: 0.0594

Step-by-step explanation:

Given : The population proportion of adults questions reported that their health was excellent : p = 0.42

Among the 14 adults randomly selected from this area, only 3 reported that their health was excellent.

i.e. Sample size : n= 14

[tex]\mu=np = 14\times0.42=5.88[/tex]

[tex]s=\sqrt{np(1-p)}=\sqrt{14(0.42)(1-0.42)}\approx1.85[/tex]

z-score : [tex]z=\dfrac{{x}-\mu}{\sigma}[/tex]

Put x= 3

[tex]z=\dfrac{3-5.88}{1.85}\approx-1.56[/tex]

Then, the probability that only 3 or fewer report having excellent health:-

[tex]P(z\leq-1.56)=0.0593799\approx0.0594[/tex]

Hence, the required probability : 0.0594