Please answer all the parts

Biostatistics question:

For each of the following examples, state a null & alternative hypothesis. Additionally for each, please explain if youd use a one- or two-sided hypothesis test. Explain your answer.

a) Lead poisoning has been associated with learning disabilities. Lead exposure often occurs through lead paint and pipes in older homes, but is also found on imported childrens toys. The purpose of this study is to determine the source(s) of lead poisoning in a group of kindergarteners living in Washington DC. One thousand kindergarteners with lead poisoning (blood lead levels above 5 g/dL) were identified by the DC Department of Public Health. Another 1,000 children without lead poisoning (levels below 5 g/dL) were also included in the study. Each of the children was asked to compete an online survey to determine the source of lead in their environment. Data from the survey found that 150 of the children with lead poisoning and 200 children without lead poisoning attended a school with exposed lead-based paint.

b) Two areas of the United States --- Marin County, CA and Long Island, NY --- have particularly high incidence of breast cancer. In 2010, a group of investigators set out to determine if socioeconomic status (defined as earning more than $150,000 per year) was associated with breast cancer. In 2010, researchers obtained tax records for the years 2000-2005 from a randomly selected group of women living in Marin County and Long Island. Women whose average annual income during that five year period was greater than $150,000 were classified as HIGH socioeconomic status (SES); those whose average was less than $150,000 were classified as LOW SES.

c) A cluster is an unusual aggregation, real or perceived, of health events that are grouped together in time and space... (CDC, 1990). A small farming community in Montana believes there is a cluster of brain cancer among young adults (ages 18-30). A member of the community decides to start a study to determine if there is in fact a cluster of brain cancers in Montana. Using data from the U.S. Census and Montana Department of Health, she determines the rate of brain cancer in her community is 16.5 cases per 100,000 individuals. She compares this rate to the national rate of brain cancer among 18-30 year olds, which is 4.7 cases per 100,000 individuals.

d) One of the main concerns regarding the HPV vaccine is that once vaccinated teen-agers and young adults will engage in risky sexual behaviors because they have immunity to HPV, which is known to cause cervical, tongue, and mouth cancers, among others. Researchers wonder if this concern about the vaccine is valid. They seek to answer the question: Are college-aged students (all genders) who received the HPV vaccine (all 3 doses) more likely to engage risky sexual practices (defined as having either sex without a condom or more than two sexual partners) than college-aged students who did not receive the HPV vaccine? Students enrolled at 50 colleges across the United States received an email with a link to an anonymous questionnaire, which asked questions about whether they received the HPV vaccine and their sexual practices.