You might need: Calculator

Problem

X is a discrete random variable. The table below defines a probability distribution for X.
What is the expected value of X?
  • Your answer should be
  • an integer, like 6
  • a simplified proper fraction, like 3, slash, 5
  • a simplified improper fraction, like 7, slash, 4
  • a mixed number, like 1, space, 3, slash, 4
  • an exact decimal, like 0, point, 75
  • a multiple of pi, like 12, space, p, i or 2, slash, 3, space, p, i
xP, left parenthesis, X, equals, x, right parenthesis
minus, 70, point, 2
minus, 30, point, 1
30, point, 4
70, point, 3