Respuesta :
The probability that at least 20% of the graduates pass is 0.995
The given parameters are:
Graduates
[tex]\mathbf{n = 60}[/tex] -- sample size
[tex]\mathbf{p = 80\%}[/tex] --- proportion that graduates
Dropouts
[tex]\mathbf{n = 75}[/tex] -- sample size
[tex]\mathbf{p = 40\%}[/tex] --- proportion that dropout
Start by calculating the mean and the standard deviation
The mean of the graduates is:
[tex]\mathbf{\mu = np}[/tex]
[tex]\mathbf{\mu = 60 \times 80\%}[/tex]
[tex]\mathbf{\mu_1 = 48}[/tex]
The mean of the dropouts is:
[tex]\mathbf{\mu = 75 \times 40\%}[/tex]
[tex]\mathbf{\mu_2 = 30}[/tex]
The standard deviation is then calculated as:
[tex]\mathbf{\sigma = \sqrt{\frac{p_1(1 - p_1)}{n_1} + \frac{p_2(1 - p_2)}{n_2}}}[/tex]
This gives
[tex]\mathbf{\sigma = \sqrt{\frac{80\% \times (1 - 80\%)}{60} + \frac{40\%(1 - 40\%)}{75}}}[/tex]
[tex]\mathbf{\sigma = \sqrt{0.0027 + 0.0032}}[/tex]
[tex]\mathbf{\sigma = \sqrt{0.0059}}[/tex]
Take square root of 0.0059
[tex]\mathbf{\sigma = 0.07681}[/tex]
The required probability is the probability that at least 20% of the graduates pass.
This is represented as:
[tex]\mathbf{P(p_1 - p_2 \ge 0.20)}[/tex]
Using normal cdf at [tex]\mathbf{\sigma = 0.07681}[/tex] and [tex]\mathbf{mu = 0.4}[/tex], we have:
[tex]\mathbf{P(p_1 - p_2 \ge 0.20) = 0.995}[/tex]
Hence, the probability that at least 20% of the graduates pass is 0.995
Read more about probabilities at:
https://brainly.com/question/6476990