exam 1 actual test
botox was approved for preventing excessive armpit sweating in adults in 2004. a clinical trial later examined its effectiveness in teenagers aged 12 to 17 years. participants received either a botox injection or a placebo injection and were examined four weeks later to see whether their sweating had been reduced by 50% or more. the results are in the table below what is the estimated probability that a teenager who received botox would have their sweating reduced by 50% or more? round your answer to two decimal places
0.80
suppose that we have the following five-number summary of the daily temperature data in the month of december from a city of iowa: minimum=14, Q1=32, median=34, Q3=38, maximum=46. which of the following answers is considered a potential outlier
14 - use the E(x) equation on the formula sheet
a class of n=21 students had scores on an exam as graphed below. approximately what percentage of students scored less than a 92 on the exam? (no two students had the same score)
14% of students 3/21=14%
suppose that data shows that 1.5% of STAT 302 students become medical doctors (having an MD degree and seeing patients). also, suppose that about 15% of TAMU undergraduates take STAT 302. out of 1000 randomly chosen TAMU undergraduates, on average how many students will be medical doctors and have taken (or will be taking) STAT302
2.25
in the 2010 US census, one of the questions asked was "how many people live in your household". the table below shows the probability distribution of this variable, x. what is the expected value for X
2.501 use the (X times P)+
the boxplot below shows the distribution of heights of 16 undergraduate statistics students. using this boxplot, approximately how many students are 69 inches or taller
4 16/4=4? bc 25%?
using the histogram on the left and the four box plots on the right below, which boxplot matches the histogram? the red dots on the histogram indicate the mean of the distribution. note that the x-axis on the histogram corresponds to the y-axis on the boxplots
B
the forced expiratory volume (FEV) is a primary indicator of lung function: it corresponds to the volume of air that can be blown out in one second after inhaling. researchers are interested in studying n=264 children ages 11-19; below is a graph of their FEV value what can we learn from this graph
about 12% of the children had an FEV between 2 and 2.5
for 218 alligators captured in four different lakes, researchers classified the primary food choice (in volume) found in alligator's stomach in one of the following categories: fish, invertebrate, reptile, bird, or other and visually displayed the data in the following graphs. what type of graph is this? be as specific as possible
bar plot
the histogram shown below represents 40 students' scores on a statistics exam
bimodal
a researcher wants to determine if a new exercise program helps people lose weight. she recruits over 1200 subjects (her statistician determined this number from sample size calculations) and randomly assigns them to either participate in the new exercise program to exercise 3 times a week and tell those in the no exercise group that they should not exercise for the duration of the study. based on the information, which of the following principles of experimental design is not used in this study
blinding
an ecologist has taken a random sample of 34 blue catfish and wants to describe the distribution of their lengths, as shown in the plot below. which of the following measurements of center and variability are best for describing this distribution
center: mean, variability: standard deviation
in a study on voters' behavior in texas, the sample is chosen by first dividing the population into voting districts. several districts are then randomly chosen and all voters within the chosen districts are included in the sample. what form of sampling is this?
cluster sampling
suppose that you wanted to study the proportion of TAMU students that like math, so you stood in front of the math building and asked some students that walked in whether or not they liked math or not. what kind of sample is this, and why might it be problematic
convenience sample; the students who are entering the math building are more likely to be math majors that like math. thus, your conclusion would overestimate the true proportions of TAMU students who like math
suppose i flip a fair coin 5 times. is flipping HHHHH more or less likely than flipping HTTHT? why
equally likely; since the coin is fair and the flips are independent, both have a (1/2)^5 chance of occurring
based on the scatterplot below, which of the following statements is correct about the head length and skull width of possums
head length and skull width are positively associated
for the following hypothetical distribution of the weight of young adults from college station, which points represent the mean and the median
mean: point B, median: point B
a paper surveyed 1076 asthma patients, asking them two questions: question 1: do conventional asthma medications usually help your asthma symptoms question 2: do you use complementary therapies (such as herbs, acupuncture, aroma therapy) in the treatment of your asthma the table below summarizes the results are the events that medications usually don't help and using complementary therapies independent? why or why not
no, because when medications don't help, people are more likely to use complementary therapies than they would have been in general
the events A is that a randomly selected person is male, and even B is that a randomly selected person is pregnant. if these two events A and B are disjoint (or mutually exclusive), and both P(A) and P(B) >0, then they are
not independent P(A) and P(B) = 0 to be independent
suppose that a researcher evaluates her research claim that the average systolic blood pressure for adults in age 20-60 is higher than 120 which has been used as a guideline as a normal systolic blood pressure for decades. in her study, the average blood pressure of 200 randomly selected individuals who did not have any health issues was 123.6 in this study, the average blood pressure of adults that she wanted to investigate was a __, and the average blood pressure of the 200 sampled individuals is a __
parameter; sample statistic
doctors are interested in studying whether playing video games might distract teenage patients during a minor procedure and thereby decrease the sensation of pain. because they are concerned that patients with less experience playing video games may be either more or less focused on the game than those with more experiences, they decide to first place the 12 patients with more video game experience in group A and then place 12 patients with less experience in group B. then they randomly assigned 6 of the patients with more experience and 6 of the patients with less experience to play video games during the procedure. the remaining patients were told to breathe deeply. what type of study is this
randomized experiment with blocking
why is a sample standard deviation (s) often used instead of sample variance (s^2) to describe variation in a data set
sample standard deviation has the same units as the data, so the interpretation is more intuitive
the educational testing service (ETS) needed a sample of colleges. ETS first divided all colleges into 6 subgroups of similar types (small public, small private, medium public, medium private, large public, and large private). then they randomly selected 3 colleges from each group. the sampling method used is
stratified random sample
texas a&m wants to conduct a survey to determine which students think about a change in student fees. they randomly select a UIN and then sample every 50th UIN after that until they reach 300 students. They is a __ sample
systemic random sample
adam wants to find out whether the proportion of undergraduate freshman who are first-generation students is about the same as the proportion of total undergraduates who are first-generation students, which is 25%. he randomly selected 100 of the 54,476 freshmen undergraduate students at texas a&m and asked them if they were first-generation students; 22 of them said they were what is the sample?
the 100 randomly selected freshmen undergraduate students at texas a&m
taylor swift is interested in learning what proportion of her fans watched her premiere betty live at the ACM awards on september 16, 2020. she takes a simple random sample of 500 fans and ask them. of the 500 fans, 475 of them (95%) respond that they watched her perform. what is the statistic and what is its value
the statistic is the proportion of the sampled taylor swift fans who watched the performance, which is 0.95
a certain region has a population of 5 million. on any given day, the probability that a randomly selected resident decides to visit the amusement park is 1/4000. assume that each resident's decision to visit is independent of the other residents. what is the probability that all the residents of this region will decide to go to the amusement park tomorrow (assuming the amusement park is open tomorrow)?
very close to zero
tree shrews are small mammals that are related to primates. a research team examined paw preference among 30 tree shrews when grasping food out of a tube too small to simply use their snouts. they found that 13 (43%) were left pawed, 14 (47%) were right-pawed, and three (10%) didn't display a strong preference. what was/were the variable(s) of interest in this study
which paw each tree shrew preferred (left, right, or neither)
of the following graphs, which has the SMALLEST standard deviation? all data was randomly generated with a sample size of n=50, and all values of all the data are between 0 and 10. be aware that the graphs are out of order on your answers
yellow graph
the following stacked bar graphs shows the relationship between types of food (organic vs conventional) and whether or not pesticides were present. based on the graph, does it appear as though there is an association between food type and pesticide status
yes, because the conditional proportions are different in two groups