Alex wants to buy packs of gaming cards until she gets a certain card she wants, but she only has enough money to buy at most two packs. Suppose that each pack has a 20\%20%20, percent chance of containing the card she wants, and each pack costs \$10$10dollar sign, 10. The table below displays the probability distribution of XXX, the amount of money Alex spends on these cards. X=\text{money spent}X=money spentX, equals, start text, m, o, n, e, y, space, s, p, e, n, t, end text \$10$10dollar sign, 10 \$20$20dollar sign, 20 P(X)P(X)P, left parenthesis, X, right parenthesis 20\%20%20, percent 80\%80%80, percent Given that \mu_X=\$18μ X =$18mu, start subscript, X, end subscript, equals, dollar sign, 18, calculate \sigma_Xσ X sigma, start subscript, X, end subscript. Round your answer to two decimal places.