If a distance-time graph contains the point (4, 15), what does that tell you about the runner?

Explanation:

It is given that there is distance time graph. The slope of any distance time graph will give the speed or velocity of the object.

In the context, it is seen that there is a point in the distance - time graph. And the values of the point in the graph is (4,15).

Now here, the distance is plotted in the  ordinate or the vertical y-axis while time is plotted in the abscissa or the horizontal x-axis.

Thus the point (4,15) tells us that the object has traveled 15 units in time equal to 4 seconds.

the part of the wave he is travelling on is the crest

answer: at 24 february, 2014 the population gets twice of its initial population.

explanation:

since we have given that

the population for alpha city, t years after january 1, 2004 is given as

first we find out the initial population, i.e. t=0,

so, our quadratic equation becomes,

according to question, we have said that if the population has twice its initial population, then it becomes

so, time taken to reach this above mentioned population is given by

now, we know that time can't be negative so, we take t=9.149 years.

hence, at 24 february, 2014 the population gets twice of its initial population.