Help please ? this is my second to last question.

Acircle has a circumference of 28.36 units what is the diameter of the circle

For what value of (y) is 3^3/3^y =1/9

Which of the following are independent events? a) knowing that it is going to rain tomorrow, and bringing an umbrella to schoolb) knowing that you have to get up early tomorrow, and going to bed before 9 p.mc) knowing that it is going to rain tomorrow, and going to bed before 9 p.md) knowing that you have a test in school tomorrow, and studying thw night before