Answer:
f(x) = 4(1.02)^(7x); spreads at a rate of approximately 2% daily
Step-by-step explanation:
The weekly number of people infected is:
f(x) = 4(1.15)^x
So the daily number of people infected is:
f(x) = 4(1+r)^(7x)
To find the value of the daily rate r, we set this equal to the first equation.
4(1.15)^x = 4(1+r)^(7x)
(1.15)^x = (1+r)^(7x)
(1.15)^x = ((1+r)^7)^x
1.15 = (1+r)^7
1.02 = 1+r
r = 0.02
So the equation is f(x) = 4(1.02)^(7x), and the daily rate is approximately 2%.
1.4 = 140% because you have to move the decimal point two places to the right to convert a number to a percentage.
We have been given that Mark had $436.
Further, we are given that Chris has $86 lesser than what mark had.
Let us assume that Chris has $x. Therefore, we can set up an equation:
(Amount Chris had) + $86 = (Amount Mark had)
Upon subtracting 86 from both the sides, we get:
Therefore, the required expression that represent the amount of money that Chris had is 
.
