I'll do the first two to get you started
===============================================
Problem 1
A = 3 = starting value
B = 10 = ending value
C = percent change
C = [ (B - A)/A ] * 100%
C = [ (10-3)/3 ] * 100%
C = (7/3) * 100%
C = 2.3333333 * 100%
C = 233.33333%
C = 233.3%
The positive C value means we have a percent increase. If C was negative, then we'd have a percent decrease.
<h3>Answer: 233.3% increase</h3>
===============================================
Problem 2
A = 9 = start value
B = 20 = end value
C = percent change
C = [ (B - A)/A ] * 100%
C = [ (20-9)/9 ] * 100%
C = (11/9)*100%
C = 1.2222222222*100%
C = 122.22222222%
C = 122.2%
<h3>Answer: 122.2% increase</h3>
What is the price of the water bottles
Notice the following pattern:
2 - 0 = 2
6 - 2 = 4
12 - 6 = 6
20 - 12 = 8
It's reasonable to assume that consecutive terms in the sequence differ by increasing multiples of 2, so that for the next number (call it x) we expect to see
x - 20 = 10 ==> x = 30
and for the number after that (call it y) we would see
y - x = y - 30 = 12 ==> y = 42
The exponential function
f(x) = a^x
can pass through all points as long as x is any real number
As an example, we can choose values of x.
x = -4, x = 0, x=100
The value of the function in terms of a would be
f(-4) = a^-4
f(0) = a^0 = 1
f(100) = a^100