Maths question (f.2)

1)A bullet hits an apple at a measured speed of 500m/s,correct to the nearest 10m/s.Find the possible range of the actual speed of the bullet.
2)Sam measures the wing spread of a butterfly to be 9.0 cm.Find the relative error of the measurement.
3)The playing time of a song is measured to be 3 minutes 27 seconds and the error s at most 1 second.Find the percentage error of the measurement,correct to 2 sig.fig.