Identify the common difference in the sequence shown below: -9, -13, -18, -23,...

-4
4

As a manufacturer of golf equipment, the spalding corporation wants to estimate the proportion of golfers who are left-handed. how many golfers must be surveyed if we want 99% confidence that the sample proportion has a margin of error of 0.025? assume that a previous study suggests that 20% of golfers are left-handed.