4-5

4-5

Complete the given function growth that will calculate how many years until a town reaches a given population.  The population will begin at a given start population.  At the end of each year, the population will grow by a given percent, and then the population will change by a constant value called aug (inhabitants coming or leaving each year).  Calculate how many years until it reaches the given goal population.
 
Note: Population should always be an integer, so always remove any decimal portion after each year.  (Always round down)
 
Input Format:
The function will have 4 arguments
start - the initial population
percent - the percentage of population growth each year.  (ex:  2  represents 2% growth)
aug - the constant number of inhabitants coming or leaving each year
goal - the population to meet or exceed
 
Remember to convert the percent parameter to a decimal value so you can use it.  (If the percent is 5, you should convert it to 0.05)
 
Output Format:
The function will return the number of years after which the goal has been met.  This number should be an integer.
 
Sample Input 1:
start:  1000,  percent:  2,  aug:  50,  goal:  1200
 
Sample Output 1:
3
 
Explanation 1:
At the end of the first year there will be:  
1000 + 1000 * 0.02 + 50 => 1070 inhabitants 
At the end of the 2nd year there will be: 
1070 + 1070 * 0.02 + 50 => 1141 inhabitants (number of inhabitants is an integer) 
At the end of the 3rd year there will be: 
1141 + 1141 * 0.02 + 50 => 1213 
It will need 3 entire years.
 
Sample Input 2:
start:  100,  percent:  10,  aug:  -5,  goal:  200
 
Sample Output 2:
13
 
Explanation 2:
The population begins at 100 before the first year.  At the end of each year, the population grows by 10%, and then 5 people leave.  After 13 years, the population is at least 200.
 
 
 function growth(pop, percent, aug, goal) {

 var years = 0 ;
 percent /= 100;
 
 while(pop < goal) {
 	pop += Math.floor(pop * percent) + aug;
 	years++;
 }
 
 return years
 
	
}

growth(1000,2,50,1200)