I will do the hypothesis test.
The null hypothesis is: p <= 0.21
The alternative hypothesis is: p > 0.21
Since the confidence interval for this problem is 95%
The critical value for this is 1.960
So the alpha is .05, the p value is equal to 0.05/2 = 0.025 since it is a 2 tailed test. (letter b)
So p value = 0.025 < 0.5, therefore, reject null hypothesis. More than 21% like the new soft drink.