Evaluate this expression: 39 ÷ (2 + 1) − 2 × (4 + 1).

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

Assume that 1400 births are randomly selected and 1378 of the births are girls. use subjective judgment to describe the number of girls as significantly high, significantly low, or neither significantly low nor significantly high. choose the correct answer below. a. the number of girls is neither significantly low nor significantly high. b. the number of girls is significantly high. c. the number of girls is significantly low. d. it is impossible to make a judgment with the given information.

What does independent variable and dependent variable mean in math?