Soru

Zorluk: OrtaLinear and Exponential Growth

An agricultural department monitored the population of honeybee colonies in two adjacent conservation areas starting in 2018 (t=0t = 0). In Area 1, the number of colonies increases by a constant 230 colonies each year. In Area 2, the number of colonies increases by a constant 10% each year. At t=0t = 0, both areas had 2,000 colonies. If the model for Area 1 predicts LL colonies at t=3t = 3 and the model for Area 2 predicts EE colonies at t=3t = 3, what is the value of LEL - E?

Cevap: 28

Cevap

28
To find the value of LEL - E, the populations projected by each model at t=3t = 3 must be calculated.

For Area 1, the growth is linear with an initial population of 2,000 and a constant annual increase of 230. The model is L(t)=2000+230tL(t) = 2000 + 230t. At t=3t = 3, the population is L(3)=2000+230(3)=2690L(3) = 2000 + 230(3) = 2690.

For Area 2, the growth is exponential with an initial population of 2,000 and a constant annual increase of 10%. The model is E(t)=2000(1.10)tE(t) = 2000(1.10)^t. At t=3t = 3, the population is E(3)=2000(1.10)3=2000(1.331)=2662E(3) = 2000(1.10)^3 = 2000(1.331) = 2662.

Subtracting the exponential model output from the linear model output yields LE=26902662=28L - E = 2690 - 2662 = 28.

Adım Adım Çözüm

1
Model the population growth for Area 1.
L(t)=2000+230tL(t) = 2000 + 230t. For t=3t = 3, L(3)=2000+230(3)=2000+690=2690L(3) = 2000 + 230(3) = 2000 + 690 = 2690. Thus, L=2690L = 2690.
Since Area 1 increases by a constant number of colonies (230) each year, its growth is linear. The initial population is 2,000.
2
Model the population growth for Area 2.
E(t)=2000(1.10)tE(t) = 2000(1.10)^t. For t=3t = 3, E(3)=2000(1.10)3=2000(1.331)=2662E(3) = 2000(1.10)^3 = 2000(1.331) = 2662. Thus, E=2662E = 2662.
Since Area 2 increases by a constant percentage (10%) each year, its growth is exponential with a growth factor of 1+0.10=1.101 + 0.10 = 1.10.
3
Calculate the difference LEL - E.
LE=26902662=28L - E = 2690 - 2662 = 28.
We need to find the difference between the linear model's prediction and the exponential model's prediction at t=3t = 3.

Anahtar Kavram

Linear growth increases by a constant amount per unit of time, whereas exponential growth increases by a constant percentage (or multiplies by a constant factor) per unit of time.

Alternatif Yöntem

Instead of setting up equations, the population values can be calculated step-by-step for each year.
Year 1 (t=1t = 1):
Area 1: 2000+230=22302000 + 230 = 2230
Area 2: 2000×1.10=22002000 \times 1.10 = 2200

Year 2 (t=2t = 2):
Area 1: 2230+230=24602230 + 230 = 2460
Area 2: 2200×1.10=24202200 \times 1.10 = 2420

Year 3 (t=3t = 3):
Area 1: 2460+230=26902460 + 230 = 2690
Area 2: 2420×1.10=26622420 \times 1.10 = 2662

Subtracting the two values at Year 3 gives the final result: 26902662=282690 - 2662 = 28.
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