The relationship if time according to the speed of light can be represented using Lorentz' time-dilation equation:
T = To / sqrt( 1 - (v^2/c^2) )
Where:
T = new time = ?
To = original time = 1 minute
v = velocity = 0.6c
c = speed of light
Substituting the given values:
T = 1 / sqrt( 1 - (0.6c^2/c^2) )
T = 1 / sqrt( 1 - (0.6^2) )
T = 1.25
Therefore, the alarm clock would ring for 1.25 minutes.