a survey asks a random sample of 2500 adults in ohio if they support an increase in the state sales tax from 5.25% to 5.50%, with the additional revenue going to education. let x denote the number in the sample that say they support the increase. suppose that 30% of all adults in ohio support the increase. 8. the mean of x is a. 30. b. 525. c. 750. d. 1750. 9. the standard deviation of x is a. 22.91. b. 27.39. c. 5255. d. 750. 10. the probability that x is at least 800 is a. less than 0.0001. b. about 0.015. c. 0.025. d. 0.05.