Suppose you have a sample of 840 people and 672 would buy the product What is a 95% confidence interval for proportion? Use the fact that 95% of sample proportions are within 1.96 standard errors of the population proportion O a. between 0.7729 and 0.8271 O b. between 0.3729 and 0.8671 O c. none of the other options is correct O d. between 0.7729 and 0.8371what is the only plausible value of correlation r based on the following scatterplot 0 1000 2000 3000 4000 5000 6000 0 -100 -200 -300 -400 -500 -600 X O a. 0.1 O b. 0.98 O c. -0.98 O d. -20