Which of the following will definitely show up next to me at the end of the December?

Consider a cube that has sides of length l. now consider putting the largest sphere you can inside this cube without any point on the sphere lying outside of the cube. the volume ratio -volume of the sphere/ volume of the cube is 1. 5.2 × 10−1 2. 3.8 × 10−1 3. 1.9 4. 2.5 × 10−1 5. 3.8

What is the value of x in the equation 1.5x+4-3=4.5(x-2)?

What is the point of inflection for the function f(x)=2cos4x on the interval (0, pi/2)