The following table shows the probability of rolling the numbers 1 through 7 on a fair 7-sided die.
х 1 2 3 4 5 6 7
P(x)1/7 1/7 1/7 1/7 1/7 1/7 1/7
What is the standard deviation of the random variable x, “the number that comes up on the die"?

Students are given 3 minutes for each multiple-choice question and 5 minutes for each free-response question on a test. there are 15 questions on the test, and students are given 51 minutes to take it. how many multiple-choice questions are on the test?

Factor the polynomial 4x4 – 20x2 – 3x2 + 15 by grouping. what is the resulting expression? (4x2 + 3)(x2 – 5) (4x2 – 3)(x2 – 5) (4x2 – 5)(x2 + 3) (4x2 + 5)(x2 – 3)

Lines a and b are parallel. what is the value of x? -5 -10 -35 -55