If the amplitude is equal to 0.25m, then the distance travelled above and below the equilibrium is also equals to 0.25m. it means if it starts above the equilibrium, one period will be completed when it returns back to its original position so, it travels 0.25 below, 0.25m back, 0.25m down and o.25 m when it comes back to its original position, so the total distance we get is by adding 0.25m 4 times that is 1m.
