**Given Information:**
- The object starts from rest.
- It travels 20 m in the first 2 seconds.
- It travels 160 m in the next 4 seconds.

**Calculating Average Velocity:**
To find the average velocity, we can use the formula:

Average Velocity = Total Displacement / Total Time

In this case, the total displacement is the sum of the distances covered in the first 2 seconds and the next 4 seconds, which is 20 m + 160 m = 180 m. The total time is 2 seconds + 4 seconds = 6 seconds.

Average Velocity = 180 m / 6 s = 30 m/s

**Calculating Final Velocity:**
To find the final velocity after 7 seconds, we need to consider the acceleration of the object. Since the object starts from rest, we can assume it has constant acceleration.

Using the equation of motion:

Final Velocity = Initial Velocity + (Acceleration * Time)

Here, the initial velocity is 0 m/s and the time is 7 seconds. We need to find the acceleration.

**Calculating Acceleration:**
The formula to calculate acceleration is:

Acceleration = Change in Velocity / Time

In the first 2 seconds, the object covered a distance of 20 m, so the velocity at the end of the first 2 seconds would be:

Velocity = Distance / Time = 20 m / 2 s = 10 m/s

The acceleration during this time interval can be calculated as:

Acceleration = Change in Velocity / Time = (10 m/s - 0 m/s) / 2 s = 5 m/s²

**Calculating Final Velocity:**
Now that we have the acceleration, we can calculate the final velocity.

Final Velocity = 0 m/s + (5 m/s² * 7 s) = 35 m/s

Therefore, the velocity after 7 seconds from the start is 35 m/s.

We haveu=0m/ss=20mt=2sfrom second eq of motions=ut+1/2at square20=0*2+1/2a2 square20=2aa=10m/s squarev at the end of 2sv=u+atv=0+10*2v=20m/ssimilarly find a after 4sa=10m/sit shows that acceleration is uniformthen velocity at the end of 7s from startv=u+atv=0+10*7v=70m/s