How do you solve this problem?

Question

At the beginning of 2010 there were 1000 giraffes in a reserve. after T years the number of giraffes J is given by the expression 1000 (1.05)^t
After how many years (approximate to the whole) the reserve will have 1150 giraffes be held in the reserve?

ANSWERS:
A) 4
B)2
C)5
D)3
E)1

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Answer 1 · 2017-12-07T23:47:37

#t=3#

We have equation:

#A(t)=1000(1.05)^t#

1150 giraffes in reserve after t years, so:

#1150=1000(1.05)^t#

We solve for #t#:

Divide both sides by 1000:

#1150/1000=(1.05)^t#

#1.15=(1.05)^t#

Take logs of both sides:

#ln(1.15)=tln(1.05)#

#ln(1.15)/ln(1.05)=t=>t=2.864551591#

#t= 3# to nearest whole number.