Allergic reactions to poison ivy can be miserable. plant oils cause the reaction. researchers at allergy institute did a study to determine the effects of washing the oil off within 5 minutes of exposure. a random sample of 1000 people with known allergies to poison ivy participated in the study. oil from the poison ivy plant was rubbed on a patch of skin. for 500 of the subjects, it was washed off within 5 minutes. for the other 500 subjects, the oil was washed off after 5 minutes. the results are summarized in the table. reaction within 5 minutes after 5 minutes row total none 420 50 470 mild 60 330 390 strong 20 120 140 column total 500 500 1,000 what is the probability that a person selected at random had no reaction. express your answer as a decimal rounded to the nearest hundredth.

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 two square pyramids are similar. find the total volume of both pyramids if the ratio of their surface areas is 9/16

The height of a plant, in inches, p years after planting it is given by the polynomial function r(p) = -2p% + 270p. find the height of the plant when p = 90 years.