Lin runs 5 laps around a track in 8 minutes. If Lin runs 21 laps at the same rate, how long does it take her?

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.