## EXPERT ANSWER

a)

Ho : p = 0.3

H1 : p < 0.3

b)

Type I error is concluding that less than 30% of custimers like it while in actual it equal or greater than 30%

Type I error is concluding that equal to or greater than 30% of custimers like it while in actual it less than 30%

or

type I error is when current ad compaign is changed when it should not be changed

Type II error is when current ad compaign is not changed when it should be changed

c) Z test for one proportion

d)

Ho : p = 0.3

H1 : p < 0.3 (Left tail test)

Level of Significance, α = 0.05

Number of Items of Interest, x = 84

Sample Size, n = 300

Sample Proportion , p̂ = x/n = 0.2800

Standard Error , SE = √( p(1-p)/n ) = 0.02646

Z Test Statistic = ( p̂-p)/SE = (0.28-0.3)/0.0265= -0.7559

critical z value = -1.645 [excel function =NORMSINV(α)]

p-Value = 0.2248 [excel function =NORMSDIST(z)]

Decision: p value>α ,do not reject null hypothesis

There is not enough evidence that to conclude that current ad compaign should be changed