Question

Netflix stock prices have climbed since it was first introduced in 2002. A stock broker is interested in estimating the mean opening price for one share of Netflix stock. To do this, a random sample of 51 days from 2014 was taken, and the opening price of one share of the stock was recorded. The sample data is summarized in the StatCrunch output:

Summary statistics: Column n Mean Std. dev. Median Range Min MaxQ1 Q3 Opening Price 51 409.6449 49.881232 428.19 166.49 317.16 483.65 365.66 448.69

• With 98% confidence, we estimate the mean opening price for a share of Netflix stocki is between $___ and $___. (Round the limits of your interval to 4 decimal places.)
• In October 2014, HBO announced it will offer a stand-alone streaming service in 2015. Since the announcement, the mean opening price of a share of Netflix stock was $374.9019. Based on the interval above, does it seem that HBO’s announcement has had an effect on Netflix stock? SELECT ONE
  • The HBO announcement seems to have had no effect on the price of Netflix stock.
  • The price of Netflix stock has risen since the announcement by HBO.
  • The price of Netflix stock has dropped since the announcement by HBO.
• Based on the histogram below, would you expect to see a linear or non-linear pattern if a qq-plot were constructed for this data? SELECT ONE
  • The qq-plot would be linear because the histogram is normally distributed.
  • The qq-plot would be non-linear because the histogram is normally distributed.
  • The qq-plot would be linear because the histogram is not normally distributed.
  • The qq-plot would be non-linear because the histogram is not normally distributed.

CDC's National Asthma Control Program was created in 1999 to help the millions of people with asthma in the United States control their disease. According to a report released in 2010, 35.2% of US adults have intermittent asthma (meaning their asthma is well-controlled without long-term medication). In order to update the report, the CDC sampled 2780 adults and found that 927 of those sampled had intermittent asthma. Test the appropriate hypotheses to determine if the percentage of US adults with intermittent asthma has changed from the value reported by the CDC. Use a significance level of 0.05.

• HoHo: _____ (p ȳ μ p̂  ? > = ≠ <) ____ HaHa:_____ (p p̂ ȳ μ  ? > < ≠ =) ____
• αα = ____
• Test Statistic: ?__ (z, t) = ____ (Note: round the test statistic to two decimal places)
• probability = ___ (0.0206 0.9794 0.0412)   
• decision: _____ (Reject H₀ Fail to reject H₀)
• At the 0.05 level, there ___ (is not is) significant evidence to conclude the percentage of US adults with intermittent asthma is ____ (less than different than greater than) 35.2%.

Answer 1

x̅ = 409.6449, s = 49.8812, n = 51

1) 98% Confidence interval :

At α = 0.02 and df = n-1 = 50, two tailed critical value, t-crit = T.INV.2T(0.02, 50) = 2.403

Lower Bound = x̅ - t-crit*s/√n = 409.6449 - 2.403 * 49.8812/√51 = 392.8586

Upper Bound = x̅ + t-crit*s/√n = 409.6449 + 2.403 * 49.8812/√51 = 426.4312

392.8586 < µ < 426.4312

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2) The price of Netflix stock has dropped since the announcement by HBO.

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3) The qq-plot would be non-linear because the histogram is not normally distributed.

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n = 2780, x = 927

p̄ = x/n = 0.3335

Null and Alternative hypothesis:

Ho : p = 0.352

H1 : p ≠ 0.352

α = 0.05

Test statistic:

z = (p̄ -p)/√(p*(1-p)/n) = (0.3335 - 0.352)/√(0.352 * 0.648/2780) = -2.05

p-value = 2*(1-NORM.S.DIST(ABS(-2.05), 1)) = 0.0412

Decision: Reject H₀.

At the 0.05 level, there is significant evidence to conclude the percentage of US adults with intermittent asthma is different than 35.2%.