Lily takes 3 hours to travel from place A to place B at the rate of 60 miles per hour . She takes 2 hours to travel from B to c with50% increased speed .find the average speed from place A to C

The average speed form A to C is 72 miles/hour

Explanation:

Average Speed

If an object travels a distance d in a time t regardless of the direction, the average speed is the quotient of the distance over the time:

Lily travels from A to C in two steps:

First, she takes ta=3 hours from A to B at va=60 miles/hour. The distance traveled in that time is:

da=va*ta

da=3*60 = 180

da = 180 miles

Then she takes tb=2 hours to travel from B to C at a speed 50% increased with respect to va, thus:

vb=150*va/100=1.5*60=90

vb=90 miles/hour

She travels a distance:

db=2*90=180 miles

The total distance traveled is

dt=180 + 180 = 360 miles

And the total time taken is

tt= 3 + 2 = 5 hours

Thus, the average speed is:

The average speed form A to C is 72 miles/hour

28. evolution

29. environment, survive, offspring  

explanation:

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.