Write a function named "json_average" that takes a json formatted string as a parameter in the format of an array of objects where each object has keys "mass", "density", "temperature", and "velocity" and each key maps to a floating point number. this function should return the average "velocity" of all the objects in the array as a json string in the format {"velocity": }

What questions about an audience should be asked during presentation preparation? check all that apply. what does the audience already know about the topic? how will multimedia tools inspire the audience? is the information interesting and engaging? how will this information affect the presentation? will the audience change the message’s purpose? what is likely to interest the audience?