Consider the situation where x = accelerated strength of concrete and y = 28-day cured strength. suppose the simple linear regression model is valid for x between 1000 and 4000 and that beta_1 = 1.25 and sigma = 350. consider an experiment in which n = 7, and the x values at which observations are made are x_1 = 800, x_2 = 1300, x_3 = 1800, x_4 = 2300, x_5 = 2900, x_6 = 3700, and x_7 = 4100. calculate sigma_beta 1, the standard deviation of beta_1 (round your answer to four decimal places.) what is the probability that the estimated slope based on such observations will be between 1.00 and 1.50? (round your answer to four decimal places.)

Martha has a deck of cards. she has lost some of the cards, and now the deck only contains nine spades, eleven diamonds, eight clubs, and twelve hearts. martha predicts that whenever she draws a card from the deck without looking, she will draw a club one-fifth of the time. which activity would best allow martha to test her prediction? a. randomly draw a card from the box and see if it is a club. b. randomly draw a card. then, continue to draw another card until all eight clubs are drawn. c. randomly draw and replace a card 120 times. then, observe how close to 30 times a club is drawn. d. randomly draw and replace a card 100 times. then, observe how close to 20 times a club is drawn.