(a). Given data:
* The velocity of the particle in the negative x-direction is,

* The velocity of the particle in the positive x-direction is,

* The time taken by the particle is,

Solution:
The acceleration in terms of velocity and time is,

Substituting the known values,

Thus, the acceleration of the particle is 1.128 meter per second squared.
(b). The velocity before the 10.9 second of the -4.36 m/s velocity is,

Thus, the value of the velocity is -16.655 meter per second.
(c). Let at time t particle will come to rest,
The time t in terms of acceleration is,

Thus, the particle will come to rest after 3.865 s since the velocity 4.36 m/s in negative x-axis.