Calculate the average speed of a biathlete who covered 20 km in 55 minutes.

To solve the problem, you must perform the following steps:

determine what quantities are known, what is required to find and write down a short condition of the problem;
determine what formulas are required to find the unknown quantity;
perform calculations.
Let us write a short condition of this problem
S = 20 km,

t = 55 min.,

v -? km / h.

Thus, the distance traveled by the biathlete and the time he spent on this path are known. It is required to find the speed of its movement.

Finding the speed of a biathlete
Recall that the distance is directly proportional to the speed of movement and time, that is, it is equal to the product of these quantities:

S = v * t,

where S is the distance measured in kilometers (km),

v is the speed of movement, measured in kilometers per hour (km / h),

t – time measured in hours (hours).

Knowing the distance and time, you can calculate the speed of movement by the formula:

v = S: t.

Calculate the speed of the biathlete.

First, it is necessary to convert the units of time measurement from minutes to hours, since, according to the condition, the time is specified in minutes, and the value measured in hours must be substituted into the formula:

55 minutes = 55/60 = 11/12 hours.

Then v = 20: 11/12 = 20 * 12/11 = 240/11 = 21 9/11 km / h = 21.82 km / h.

Answer: the speed of the biathlete was 21.82 km / h.