Optional up to 2 points of extra credit: Shown is the mean EMQ (Everyday Memory Questionnaire, a test designed to measure memory failure in everyday life) score out to three years comparing SARS-CoV-2 infected vs. uninfected individuals from a study of 111,992 individuals (Prospective Memory Assessment before and after Covid-19, N Engl J Med 2024; 390:863-865). Figure 1. Mean scores on EMQ comparing SARS-CoV-2 infected vs. uninfected individuals; higher scores indicate worse memory problems. 1. What does this graph suggest about infection with SARS-CoV-2? Please explain. Include information and descriptions from the graph to support your explanation. 2. Comparing the trendlines on the left side of the graph to the right side of the graph, what does the trend toward the right side of the graph suggest? Please hypothesize; be sure to include an explanation with supporting information. 3. Comment briefly on the sample size of this study – should this sample size give us confidence in this work? Why or why not? 4. Although the graph does not explain this, propose an explanation as to what the virus might be doing to people that could result in this outcome observed.

Consider the experiment of taking this exam. Suppose we model your score for this exam as Y=5X, where X is a sum of N iid Bernoulli random variables each with parameter p=, and N is the total number of questions. Note that X represents a random variable which is the total number of questions you get right. Find the variance of Y.

In bone-conduction testing, both cochleae are stimulated because:

Explain how speech audiometry can be used to estimate a patient’s communicative function in everyday listening environments.

Consider the experiment of taking this exam. Suppose we model your score for this exam as Y=5X, where X is a discrete uniform random variable over {0,1,…,N}, and N is the total number of questions. Note that X represents a random variable which is the total number of questions you get right. Find

Discuss the complete procedure for conducting air- and bone-conduction pure-tone audiometry, including patient instructions, clinician responsibilities, and methods for threshold determination. Make sure you add information on each of these aspects. 

You analyze the genome of an organism and measure the percentage of adenine (A) at 20%. What can you safely conclude about the percentages of the remaining nucleotides?

Pathogenic Streptococcus pneumoniae produce a polysaccharide capsule that helps them evade phagocytosis by host phagocytes, allowing them to multiply, resulting in pneumonia. S. pneumoniae that lack the capsule do not cause disease as they are readily destroyed by host phagocytes. When a mixture of living nonencapsulated and heat-killed encapsulated S. pneumoniae are injected into a mouse, the mouse dies, and living capsulated bacteria can subsequently be isolated from the mouse. Which of the following best explains this result?

Pure-tone audiometry measures hearing sensitivity across which range of frequencies?

Which speech-audiometric measure best estimates communicative function in noise?