Ulcers are sores on the lining of the digestive tract, caused by the bacteria Helicobacter pylori. You want to test the effectiveness of two new treatments for stomach ulcers. Out of 750 people with stomach ulcers, who are willing to serve as subjects, the researchers record various response variables and a number of demographic variables. For example, it was found that 100 subjects are under 18 years old, 250 subjects are 18-35 years old, 250 subjects are 35-55 years old, and 150 subjects are older than 55 years. Researchers speculated that people of different age groups would not react differently to the treatments. a. completely randomized design. b. randomized block design. c. matched pairs design.

The rate of decay of a radioactive substance depends upon the amount present initially. the mass y (mg) of the radioactive substance cobalt-60 present in a sample at time t (years) is represented by the exponential equation y=50e −0.1315 t . answer the following questions in complete sentences. 1. how does the exponential equation above compare to the equation for simple interest that is compounded continuously? explain the similarities. 2. what is the initial amount of cobalt-60 in the sample? 2. how much cobalt-60 is left after 8.4 years? show your work. 3. what would be the y-intercept of the graph? what does it represent? 4. after how many years will the amount of cobalt-60 left be 6.25 mg? explain what happens to the cobalt-60 after 50 years? 5. discuss some “real-world” examples and uses of cobalt-60

Write each of the following numerals in base 10. for base twelve, t and e represent the face values ten and eleven, respectively. 114 base 5 89t base 12

Aadc is formed by reflecting aabc across line segment ac, as shown in the figure. if the length of ac is 4 units, the area of aadc is square units.