The trainee travels by means of a scooter and is only able to depart his home after sunrise (07:00), due to broken lights . The distance from his house to the training site is 60 km. If he used a car, still departing 07:00, he would travel an average of 30 km/h faster and reach the training site 20 minutes earlier. Take the average speed of the scooter as s. Use the following variables for each quantity: time = t; average speed = s; distance = d.

Determine:
an expression for the average speed of the car

Exercise: counting committees 0.0/2.0 puntos (calificable) we start with a pool of n people. a chaired committee consists of k≥1 members, out of whom one member is designated as the chairperson. the expression k(nk) can be interpreted as the number of possible chaired committees with k members. this is because we have (nk) choices for the k members, and once the members are chosen, there are then k choices for the chairperson. thus, c=∑k=1nk(nk) is the total number of possible chaired committees of any size. find the value of c (as a function of n ) by thinking about a different way of forming a chaired committee: first choose the chairperson, then choose the other members of the committee. the answer is of the form c=(α+nβ)2γn+δ. what are the values of α , β , γ , and δ ?