A one-sided claim about a population proportion is a claim that the proportion is less than (or greater than) some specific value. Such a claim can be formally addressed using a one-sided confidence interval for p, which can be expressed as p < p̂ + E or p > p̂ - E, where the margin of error E is modified by replacing z_α/2 with z_α. (Instead of dividing α between two tails of the standard normal distribution, put all of it in one tail.) The Chapter Problem refers to a Gallup poll of 1487 adults showing that 43% of the respondents have Facebook pages. Use that data to construct a one-sided 95% confidence interval that would be suitable for helping to determine whether the proportion of all adults having Facebook pages is less than 50%.