According to an NBC News/Wall Street Journal poll released Sunday, 58 percent of registered voters expressed concern about a loosening of restrictions, compared with 32 percent who worried that the restrictions would stay in place for too long. 3 percent said they were concerned about both scenarios. A mere 3 percent said the pandemic had no impact on their lives, compared with 77 percent who said it had affected them either in "a very major way" or "a fairly major way." The sample size was 900 registered voters. a. What is the point estimator for the proportion of registered voters expressed concern about a loosening of restrictions? b. Determine the margin of error for this poll assuming a confidence level of 95%