Please answer questions of 4,5, and 6?

Suppose a sample of a certain substance decayed to 77.8% of its original amount after 300 days. (Round your answers to two decimal places.) (a) What is the half-life (in days) of this substance? 504.58 * days (b) How long would it take the sample to decay to one-third of its original amount? 504.58 days Need Help? Read It Submit Answer 5. [0/0.36 Points] DETAILS PREVIOUS ANSWERS SCALCET9 3.8.011. MY NOTES ASK YOUR TEACHER PRACTICE ANOTHER Scientists can determine the age of ancient objects by the method of radiocarbon dating. The bombardment of the upper atmosphere by cosmic rays converts nitrogen to a radioactive isotope of carbon, 14C, with a half-life of about 5,730 years. Vegetation absorbs carbon dioxide through the atmosphere, and animal life assimilates "C through food chains. When a plant or animal dies, it stops replacing its carbon, and the amount of "C present begins to decrease through radioactive decay. Therefore, the level of radioactivity must also decay exponentially. A discovery revealed a parchment fragment that had about 68% as much "C radioactivity as does plant material on the earth today. Estimate the age (in years) of the parchment. (Round your answer to the nearest hundred years.) 25750 X yr Need Help? Read It Watch It Submit Answer [0/0.41 Points] DETAILS PREVIOUS ANSWERS SCALCET9 3.8.014. MY NOTES ASK YOUR TEACHER PRACTICE ANOTHER A curve passes through the point (0, 7) and has the property that the slope of the curve at every point P is twice the y-coordinate of P. What is the equation of the curve? (Use x as the independent variable.) y(xx) = 14x + 7 X