Antti entered a $10$-kilometer race. his goal is to finish in one hour. he starts off sprinting, and completes the first $2$ kilometers of the race at an average speed of $12$ kilometers per hour.

to achieve his goal of a one-hour finish time, what average speed (in kilometers per hour) must antti maintain for the last $8$ kilometers of the race?

enter your answer as a number in decimal form, without units.

Answer: d. 39 cmin the diagram, the approximate length of the minor arc de is 39 centimetres.step-by-step explanation: the formula for the length of an arc in a circle is as displayed below.let the length of the minor arc de = xx = 2( pi )r × angle of sector / 360°from this, we will substitute the values given from the problem into the formula to obtain the length of the minor arc de.x = 2( pi )r × angle of sector / 360°r = radius = 25cmpi as an approximate value = 3.14angle of sector = 120°x = 2( 3.14 )( 25 ) × 120° / 360°x = 157 × 1 / 4x = 39.25x = 39 ( rounded to the nearest whole number as an approximate value )