Reference no: EM132336051
Statistics One Proportion Z-Test Assignment -
Q1. In the past, the proportion of women in a certain population who were taller than 63 inches was 80%. A researcher believes that this proportion has increased. In a random sample of 200 women in this population, 170 of them are taller than 63 inches. Test the researcher's claim at the significance level α = 0.05.
(a) The null hypothesis is H0: p = 0.80. (Here, p0 = 0.80). Write the alternative hypothesis.
(b) Find p^ = x/n.
(c) Calculate the test statistic using the formula
z = (p^ - P0)/(√(p0(1-p0)/n))
(d) Sketch a standard normal curve, and shade the area that represents the P-value. Find the P-value using the normaldcf on your calculator.
(e) Compare the P-value with the significance level, α = 0.05, in order to make your decision. State your decision (reject the null hypothesis or fail to reject the null hypothesis).
(f) State your conclusion.
Q2. In 2001, 38% of families reported that their family regularly ate dinner together. A researcher believes that this proportion has decreased. In a recent poll, 35.9% of 1122 families reported that their family regularly ate dinner together. Use α = 0.05. You may use the 1-PropZTest on your graphing calculator.
(a) State the null and alternative hypotheses.
(b) This time p^ = 0.359 and n = 1122 are given to you. Find x = np^. (You will need to round the result to the nearest whole number.)
(c) Give the test statistic (round to 2 decimal places): z =
(d) Give the P-value (round to 3 decimal places).
(e) State your decision.
(f) State your conclusion.
Q3. Test the hypotheses
H0: p = 0.4
H1: p ≠ 0.4
at the level α = 0.01. The sample data are n = 500, x = 220. You may use your graphing calculator.
(a) Give the sample proportion. p^ =
(b) Give the test statistic (round to 2 decimal places). z0 =
(c) Give the P-value (round to 3 decimal places).
(d) State your decision.
(e) Construct a 99% confidence interval for the population proportion.
(f) Does your confidence interval contain p0 = 0.4? Does this confirm your decision in part (d)?
(g) Suppose that everything in the original problem remains the same except that the sample data are n = 5000, x = 2200. (The sample proportion is exactly the same as it was before!) Repeat the test, and report the new test statistic, the new P-value, and your new decision.
Instructions: Must use a scientific calculator where stated.