The median of the data given below is-2. Find the
value of unknown frequency 'a':
Class-interval 0-20 20-40 40-60 | 60-80 | 80-100 100-120
Frequency 5 8 a 12 7 8

Amass weighing 16 pounds stretches a spring 8/3 feet. the mass is initially released from rest from a point 2 feet below the equilibrium position, and the subsequent motion takes place in a medium that offers a damping force that is numerically equal to 1/2 the instantaneous velocity. find the equation of motion if the mass is driven by an external force equal to f(t)=cos(2t).