inn Annual coal production in the US in billion tons per yea
Solution
t is nothing but the time interval between two successive years.For example the years are at equal intervals of 2 years (1997,1999,2001,2003.....).This t can also be calculated by number of years in between 1997-2009 divided by number of years considered i.e 14/7=2=t.
First , calculating the left hand sum=t(1.090+1.094+1.121+1.072+1.132+1.147)=13.312
Then,
calculating the right hand sum=t(1.094+1.121+1.072+1.132+1.147+1.073)=13.278
So, The amount of coal production according to left hand sum=13.312
right hand sum=13.278
