Question

Samuel Morse determined that the percentage of t's being used in the English language in the 1800's was 9%. A random sample of 600 letters from a current newspaper contained 48 t's. Test the claim that the proportion of t's has changed in modern times, using the current newspaper data and a significance level of 0.05

Answer 1

There is insufficient evidence to indicate that the population proportion of t’s in modern newspaper is different from 0.09. The result is not statistically significant

Explanation:

H0 : p0 = 0.09

H1 : p0 ≠ 0.09

Sample size, n = 600 ; α = 0.05

Decision region

Zstatistic < Zcritical ; reject H0

P = 48 / 600 = 0.08

Zstatistic = (p - p0) ÷ sqrt((p0(1 - p0)) /n)

Zstatistic = (0.08 - 0.09) ÷ sqrt(0.09(0.91))/600)

Zstatistic = - 0.01 /0.0116833

Zstatistic = - 0.856

Zcritical at 0.05, = - 1.96

Zstatistic > Zcritical

-0.856 > - 1.96

Hence, we fail to reject the Null