1. Are unnecessary c-sections putting moms and babies health at risk? The procedure is a major surgery which increases risks for the baby (breathing problems and surgical injuries) and for the mother (infection, hemorrhaging, and risks to future pregnancies). According to the Center for disease control and prevention, about 32.2% of all babies born in the U.S. are born via c-section. The World Health Organization recommends that the US reduce this rate by 10%.

Suspecting that certain states have higher rates than 32.2%, researchers randomly select 1200 babies from Florida and find that 42.8% of the sampled babies were born via c-section.

Let p be the proportion of all babies in the U.S. that are born via c-section. Give the null and alternative hypotheses for this research question.

H0: p = .322

Ha:p> .322

H0:p= .322

Ha:p .322

H0:p= .428

Ha:p .428

H0: p > .322

Ha:p= .322

2. A quality control engineer at a potato chip company tests the bag filling machine by weighing bags of potato chips. Not every bag contains exactly the same weight. But if more than 15% of bags are over-filled then they stop production to fix the machine.

They define over-filled to be more than 1 ounce above the weight on the package. The engineer weighs 100 bags and finds that 11 of them are over-filled.

He plans to test the hypotheses:H0: p = 0.15 versusHA: p > 0.15 (where p is the true proportion of overfilled bags).

What is the test statistic?

-1.12

1.12

0.03

-0.03

3. According to a Pew Research Center, in May 2011, 35% of all American adults had a smartphone (one which the user can use to read email and surf the Internet). A communications professor at a university believes this percentage is higher among community college students.

She selects 300 community college students at random and finds that 114 of them have a smartphone. In testing the hypotheses:H0: p = 0.35 versusHA: p > 0.35, she calculates the test statistic as Z = 1.07.

Use the Normal Table to help answer the p-value part of this question.

Clickhereto access the normal table.

There is not enough evidence to show that more than 35% of community college students own a smartphone (P-value = 0.1423).

There is not enough evidence to show that more than 35% of community college students own a smartphone (P-value = 0.8577).

There is not enough evidence to show that more than 35% of community college students own a smartphone (P-value = 0.2846).

There is enough evidence to show that more than 35% of community college students own a smartphone (P-value = 0.1423).