Answer:
Step-by-step explanation:
Since the grass on the field erodes by -1 1/2% every year, it means that the rate of erosion is exponential. It is therefore eroding in geometric progression. We would apply the formula for determining the sum of n terms of a geometric sequence which is expressed as
Sn = a(1 - r^n)/(1 - r)
Where
n represents the number of terms(number of years) in the sequence.
a represents the first term in the sequence(the length 3 years ago)
r represents the common ratio(rate of erosion)
From the information given,
a = 220 feet
r = - 1.5/100 = - 0.015
n = 3
Therefore, the length of the field after 3 years, S3(length of the field now) would be
Sn = a(1 - r^n)/(1 - r)
S3 = 220(1 - (- 0.015^3)/(1 - - 0.015)
S3 = 220.0007425/1.015
S3 = 216.7495 feet
