# Math homework help

## A researcher collects data on two independent samples. The first group consists

2. A researcher collects data on two independent samples. The first group consists of 20 human subjects, has a sample mean of 4.21, and a standard deviation of 1.4. The second group consists of 20 subjects, has a sample mean of 3.15, and a standard deviation of 1.8. Test the null hypothesis that there is no difference between the population means of the two groups at the .01 level of significance.

## A quality control analyst measures the number of hours a patient in a low-risk

1). A health Inspector at a restaurant will enter the kitchen & choose 5 stations to inspect from a predetermined list of 15 stations present in post restaurant kitchens.

a) How many different sets of 5 stations exist?

b) If all sets are equally likely, what is the probability of each set?

c) If the inspector were instead to randomly select 13 stations to inspect, how many different sets of 13 stations would exist?

## A professor measured the time (in seconds) required to catch a falling meter stick

1. A professor measured the time (in seconds) required to catch a falling meter stick for 19 randomly selected students’ dominant and non-dominant hand. The professor claims that the reaction time in an individual’s dominant hand is less than the reaction time in their non-dominant hand.

## Among coffee drinkers, men drink a mean of 3.2 cups per day with

**Chapter 5**

1. Total cholesterol in children aged 10-15 is assumed to follow a normal distribution with a mean of 191 and a standard deviation of 22.4.

a. What proportion of children 10-15 years of age have total cholesterol between 180 and 190?

## A health inspector at a restaurant will enter the kitchen and choose

1 A health inspector at a restaurant will enter the kitchen and choose 5 stations to inspect from a predetermined list of 15 stations present in most restaurant kitchens.

a. How many different sets of 5 stations exist?

b. If all sets are equally likely, what is the probability of each set?

c. If the inspector were instead to randomly select 13 stations .to inspect, how many different sets of 13 stations would exist?

d. If all sets were equally likely, what is the probability of each set?

## A crossover trial is planned to evaluate the impact of an educational intervention

1. Suppose we want to design a new placebo-controlled trial to evaluate an experimental medication to increase lung capacity. The primary outcome is peak expiratory flow rate, a continuous variable measured in liters per minute. The primary outcome will be measured after 6 months on treatment. The expected peak expiratory flow rate in adults is 300 with a standard deviation of 50. How many subjects should be enrolled to ensure 80% power to detect a difference of 15 liters per minute with a two sided test with ? = 0.05

## What percentage of the checkout timesas less than 3 minutes

Checkout Time (in minutes) Frequency

1.0 - 1.9 5

2.0 - 2.9 6

3.0 - 3.9 4

4.0 - 4.9 3

5.0 - 5.9 2

1. What percentage of the checkout timesas less than 3 minutes?

## 54% of men consider themselves professional baseball fans. You randomly select

54% of men consider themselves professional baseball fans. You randomly select 10 men and ask each if he considers himself a professional baseball fan. Find the probability that the number who consider themselves baseball fans is (a) exactly 8, (b) at least 8 and (c) less than eight.