The viscosity of two different brands of car oil is measured and the following data resulted: Brand 1 10.62, 10.58, 10.33, 10.72, 10.44, 10.74 Brand 2 10.50, 10.52, 10.58, 10.62, 10.55, 10.51, 10.53 Test the hypothesis that the mean viscosity of the two brands is equal, assuming that the populations have normal distributions with equal variances.
Chapter 7: Energy Balance and Weight Control Section 7.1: Energy Balance • Energy balance: the energy you take in (food) matches the energy you put out (calorie burn) - Positive energy balance: when you eat more calories than you burn. - Negative energy balance: when you eat fewer calories than you burn. • Basal metabolism (BMR): the minimum amount of calories the body needs to support itself in a fasting state (not eating). - 1 kcal/kg for men per hour - .9 kcal/kg for women per hour • Resting metabolism: the amount of calories the body uses when a person hasn’t eaten for 4 hours. • Thermic effect of food: when your metabolism is increased during the absorption, digestion, and metabolism of carbs, proteins, and fats. • Bomb calorimeter: a device that determines how many calories are in a food. Section 7.2: Determination of Energy Use by the Body • Direct calorimeter: measuring the heat released from a person’s body to determine their energy use. This is done in an insulated chamber. • Indirect calorimeter: measuring the oxygen uptake and carbon dioxide output to determine the energy used by a person’s body. Section 7.3: Assessing Healthy Body Weight • Body mass index (BMI): the weight that a person should be at based on their height. - Underweight: less than 18.5 - Healthy weight: between 18.5 and 24.9 - Overweight: between 25 and 29.9 - Obese: between 30-39.9 - Severely obese: over 40 • Ways to determine body fat content - Under water weighing: weighing a person under water on a standard scale to determine body fat. - Air displacement: when a person goes into a chamber and the volume space they take up determines their body fat. - Bioelectrical impedance: when a low energy electrical current is put through a person to see how much body fat they have. The higher the body fat, the more resistance from the current. - Dual energy x-ray absorptiometry (DEXA): multiple low energy x rays that are used to determine body composition and bone mass. This is the most accurate. Chapter 7: Energy Balance and Weight Control • Obesity: a condition where too much fat on the body can lead to further health complications. - Upper body obesity: this type of obesity is caused by insulin resistance and is also known as central/abdominal obesity, where there is excess fat in the abdominal region. (Apple shaped) o This can lead to health problems like diabetes, high blood lipids, and heart disease. - Lower body obesity: this type of obesity is triggered by estrogen and progesterone hormones and leads to larger thighs and gluteus. (Pear shaped) Section 7.4: Why Some People Are Obese—Nature Versus Nurture • Genetic and environmental factors can increase the risk of obesity. - Where your fat is stored, is determined by genetics. - Genes account for 70% of the weight differences between people. • Identical twins show the same weight gain patterns. • Humans have a thrifty metabolism—this means that their bodies store fat readily, just incase it ever needs it. • Set point theory: states that humans have a genetically pre determined body weight/fat content. • Leptin: a hormone that is made by adipose tissue, which influences the regulation of fat mass. Section 7.5: Treatment of Overweight and Obesity • Medications for weight loss: drugs that help a person lose weight. Usually used for people with a BMI of 30 or higher or a BMI of 27 to 29.9 with weight related medical conditions (heart disease, diabetes, etc.) - Amphetamine: medications that enhance central nervous system stimulation. • Obesity treatments - Very low calorie diets (VLCD): a diet that puts an obese person on 400-800 calories per day (more proteins that carbs). - Gastroplasty: a surgery where doctors staple a persons’ stomach so that they eat less. - Sleeve gastrectomy: a surgery where doctors reduce a persons’ stomach to about the size of a banana. • Types of diets - Unreliable diets: weight loss diets that typically aren’t safe and possess the following qualities o Quick weight loss o Limit food selections o Recommend expensive supplements o Claim that there is no need to exercise Chapter 7: Energy Balance and Weight Control - High protein, low carb diets: where most of a person’s calories come from protein, and minimal calories come from carbs. - Carb focused diets: where most all calories come from carbs, and minimal come from fats and proteins. - Low fat diets: where fats are kept to a minimum in a person’s diet.