Allison ran 3/8 km (0.375 km) in 3 minutes.
Set up a proportion to find how long it takes for her to run 1 km

Cross multiply to get:

Solve:

x = 8 minutes
Answer: 81
Step-by-step explanation:
6.75 + 3 + 3.75 = X
X x 6 = 81
Answer: 8 subsets----------------------------------------------------------------------
----------------------------------------------------------------------
There are n = 3 elements in the given set, so there are 2^n = 2^3 = 2*2*2 = 8 subsets. Those 8 subsets are listed below
{a,b,c}
{a,b}, {a,c}, {b, c}
{a}, {b}, {c}
{ }
The first row is the original set. Any set is a subset of itself.
The second row represents subsets with exactly 2 elements.
The third row represents subsets with exactly 1 element
The fourth row is the empty set which can be written as
-1-4x+7x=1x+4x
-1-4x+7x=1x+4x
-1+-4x+7x=x+4x
(-4x+7x)+(-1)=(x+4x)
3x+-1=5x
3x-1=5x
3x-1-5x=5x-5x
-2x-1=0
-2x-1+1=0+1
-2x=1
-2x/-2=1/2
x=-1/2
This is an exponential growth/decay problem...
F=Ir^t, F=final value, I=initial value, r=rate, t=time, in this case:
F=I(1.03)^t and they just want to know when F=2I so
2=1.03^t take natural log of both sides...
ln2=t*ln1.03
t=ln2/(ln1.03)
t≈23.45
So it will take approximately 23.45 years for the population to double..
1990+23.45=2013.45
So during the year of 2013 the population will have double from its 1990 level.