Two cards are drawn without replacement from a standard deck of 52 playing cards. What is the probability of choosing a black card for the second card drawn, if the first card, drawn without replacement, was a spade? Express your answer as a fraction or a decimal number rounded to four decimal places.

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

The radius of a sphere is 3 inches. which represents the volume of the sphere?

Which statements about the system are true? check all that apply. y =1/3 x – 4 3y – x = –7 the system has one solution. the system consists of parallel lines. both lines have the same slope. both lines have the same y–intercept. the equations represent the same line. the lines intersect.