Help me with this math I gotta get some serious help

What is the best approximation for the area of a circle with a radius of 4 m ? use 3.14 to approximate pi

If t17 = 3 (t5) in an arithmetic progression, find t1 in terms of d.

Determine the required value of the missing probability to make the distribution a discrete probability distribution. x p(x) 3 0.23 4 ? 5 0.51 6 0.08 p(4) = nothing  (type an integer or a decimal.)