arithmetic progression

Let Pk represent the perimeter of a square with sides of length k. The value of the expression P₁ + P₂ + P₃ + ⋯ + P₁₀ is

Let $$X$$ be a random variable which is uniformly chosen from the set of positive odd numbers less than $$100.$$ The expectation, $$E\left[ X \right],$$ is __________.