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galina1969 [7]
3 years ago
6

The number of trees in a rainforest decreases each month by 0.5%. The forest currently has 2.5 billion trees. Which expression r

epresents how many trees will be left in 10 years.
Mathematics
1 answer:
Blababa [14]3 years ago
5 0

Given:

Present number of trees = 2.5 billions

Rate of decrease = 0.5% per month

To find:

The expression that represents how many trees will be left in 10 years?

Solution:

Exponential decay model:

P(t)=a(1-r)^t         ...(i)

where, a is initial value, r is decreasing rate and t is time period.

We have,

a = 2.5 billions

r = 0.5% = 0.005 per month

t = 10 years = 120 months                         [1 year = 12 months]

Putting a=2.5, r=0.005 and t=120 in (i), we get

P(120)=2.5(1-0.005)^{120}

P(120)=2.5(0.995)^{120}

P(120)=1.3699657

P(120)\approx 1.37

Therefore, the required expression is 2.5(1-0.005)^{120} and the remaining trees after 10 years is about 1.37 billions.

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