Ericka observed the total variation in the water level over 6.2 years to be - 13.64 mm. She compared this to the average annual trend, which shows the water level rising 1.8 mm/year. Remember, she used 6.2 years as her time period. What is the difference between how much average water levels rose and how much the water level fell in the part of the river she observed?

Question

Frank Sampson

Mathematics

29 June, 07:24

Ericka observed the total variation in the water level over 6.2 years to be - 13.64 mm. She compared this to the average annual trend, which shows the water level rising 1.8 mm/year. Remember, she used 6.2 years as her time period. What is the difference between how much average water levels rose and how much the water level fell in the part of the river she observed?

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Athena Kelly · Answer 1

In the area that she observed, the water level fell 13.64mm over 6.4 years, for an average annual rate of change of:

-13.64 : 6.2 = - 2.2 mm / year.

The difference between how much average water levels rose and how much water levels in her part of the river fell is:

1.8 - (-2.2) = 4 mm/year

During the 6.2 year period:

4 mm/year * 6.2 = 24.8 mm