Answer: A.Validate and implement the results.
The final step in a forecasting system is to validate and implement the results. This can be similar to a presentation. After going through all the steps from the planning, researching, and gathering of data, making the forecast, validating and implementing the results will be the last thing that needs to be done. 
 
        
             
        
        
        
Answer:
Guessing you just need help with the definition but if it's the question I can still help you.
 
        
                    
             
        
        
        
Answer:
4 hertz
Explanation:
The defination of freqyency = the total no of cycle made by a wave in one second .
so,
cycle or vibrations=60
tame taken = 15
now,
 frequency = no. of cycle / time taken
 = 60/15
 =4 hertz
hence, the its frequency = 4hertz