To compare the rainfall data, India Meteorological Department (IMD) calculated the Long Period Average (LPA) of rainfall during period June-August for each of the 16 states. The figure given below shows the actual rainfall (measured in mm) during June-August, 2019 and the percentage deviations from LPA of respective states in 2018. Each state along with its actual rainfall is presented in the figure.
The LPA of a state for a year is defined as the average rainfall in the preceding 10 years considering the period of June-August. For example, LPA in 2018 is the average rainfall during 2009-2018 and LPA in 2019 is the average rainfall during 2010-2019. It is also observed that the actual rainfall in Gujarat in 2019 is 20% more than the rainfall in 2009. The LPA of Gujarat in 2019 is closest to
The actual rainfall in Gujarat in 2019 is 20% more than the rainfall in 2009.
So If the actual rainfall in 2009 = x mm
Then the actual rainfall in 2019= 1.2x mm
Actual rainfall in 2019= 600mm
Then, actual rainfall in 2009 = 500mm
As deviation is +25% so average 2009 - 2018 is 600/1.25 = 480
LPA 2019 = (480×10 - 500 + 600 )/10 = 490mm