The circumference of a circle is calculated using the following equation:

Where d is equal to the diameter (the length of a straight line from one side of the circle to the other side).
We know that the diameter of the circle given (also known as AB) is equal to 20 cm.
We can then plug this into the equation and solve for the circumference:

Since the question asks for the answer to be in terms of

, this is as far as we need to go. So
the circumference of the circle is:
or D.
Distance ran by Tara = 1600 m
Time taken by Tara to ran 1600 m = 5 min 20 seconds
We have to calculate the speed.
Firstly, we will convert the unit of time in one unit.
Time = 5 min 20 seconds
= 5 min +
min (Because 1 min = 60 sec)
= 
=
=
min
Now we will use Distance speed formula which states,
Distance = speed
time
1600 m = speed

speed = 
Speed = 300 m/min
So, the speed of Tara was 300 meter/min.
A) Olaf has 250 files, which represent 100%. 12% of that are photos which number is unknown (x).
250 files - 100%
x photos - 12%
So, the proportion should look like:
250 files : 100% = x : 12%
B) After crossing the products:
x = 250 files * 12% : 100%
x = 30 photos