A study was conducted to determine the proportion of people who dream in black and white instead of color. Among 301 people over the age of​ 55, 76 dream in black and​ white, and among 311 people under the age of​ 25, 10 dream in black and white. Use a 0.01 significance level to test the claim that the proportion of people over 55 who dream in black and white is greater than the proportion for those under 25. Complete parts​ (a) through​ (c) below.

Respuesta :

Answer:

Step-by-step explanation:

This is a test of 2 population proportions. Let 1 and 2 be the subscript for people over the age of​ 55 and people under the age of​ 25. The population proportion of people over the age of​ 55 and people under the age of​ 25 who dream in black and​ white would be p1 and p2 respectively.

p1 - p2 = difference in the proportion of people over the age of​ 55 and people under the age of​ 25 who dream in black and​ white.

The null hypothesis is

H0 : p1 = p2

p1 - p2 = 0

The alternative hypothesis is

H1 : p1 > p2

p1 - p2 > 0

it is a right tailed test

Sample proportion = x/n

Where

x represents number of success(number of complaints)

n represents number of samples

For people over the age of​ 55,

x1 = 76

n1 = 301

p1 = 76/301 = 0.25

For people under the age of​ 25,

x2 = 10

n2 = 311

p2 = 10/311 = 0.032

The pooled proportion, pc is

pc = (x1 + x2)/(n1 + n2)

pc = (76 + 10)/(301 + 311) = 0.14

1 - pc = 1 - 0.14 = 0.86

z = (p1 - p2)/√pc(1 - pc)(1/n1 + 1/n2)

z = (0.25 - 0.032)/√(0.14)(0.86)(1/301 + 1/311) = 0.218/0.02805598439

z = 7.71

From the normal distribution table, the p value is

p < 0.00001

Since 0.01 > 0.00001, we would reject the null hypothesis.

Therefore, the proportion of people over 55 who dream in black and white is greater than the proportion for those under 25.