A box contains 9 red marbles and 1 blue marbles. Nine hundred random draws are made from this box, with replacement. What is distribution of the number of red marbles seen, roughly?

Respuesta :

Answer:

Then, the distribution for x="number of red marbles seen in 900 draws" is a normal distribution with mean = 810 and standard deviation = 9.

Step-by-step explanation:

As there are draws with replacement, it would have been modeled by a binomial distribution, with n=900 and p=9/10=0.9.

But because n is too large to keep binomial calculus simple, it can be approximated by a normal distribution, with parameters:

[tex]\mu=np=900*0.9=810\\\\\sigma=\sqrt{np(1-p)}=\sqrt{900*0.9*0.1} =\sqrt{81}=9[/tex]

Then, the distribution for x="number of red marbles seen in 900 draws" is a normal distribution with mean = 810 and standard deviation = 9.