Which of these represents the probability of getting doubles (getting the same number on two dice) on or before the seventh roll of two six-sided dice?

Question

Which of these represents the probability of getting doubles (getting the same number on two dice) on or before the seventh roll of two six-sided dice?

A. None of these

B. P(X = 1) + P(X = 2) + P(X = 3) + P(X = 4) + P(X = 5) + P(X = 6) + R(X = 7)

C. geometpdf(1/6,7)

D. (5/6) ^ 0 * (1/6) + 2 * (5/6) ^ 1 * (1/6) + 3 * (5/6) ^ 2 * (1/6) ^ 1 + 4 * (5/6) ^ 3 * (1/6) ^ 1 * 4 5(5/6)4(1/6)+6(5/6)5(1/6)1 +7(5/6)6(1/6)1

OE binomial(10,7) * (1 - 1/6) ^ 52 * (1/6)

Answer 1

D. (5/6) ^ 0 * (1/6) + 2 * (5/6) ^ 1 * (1/6) + 3 * (5/6) ^ 2 * (1/6) ^ 1 + 4 * (5/6) ^ 3 * (1/6) ^ 1 + 5 * (5/6) ^ 4 * (1/6) + 6 * (5/6) ^ 5 * (1/6) + 7 * (5/6) ^ 6 * (1/6)