Question 1126437
the formula to use with this is f = p * (1 + r) ^ t


f is the future value
p is the present value
r is the interest rate per time period
t is the number of time periods.


you are given that the number of the bacteria is increasing at the rate of 5% per hour.


your time period is therefore in hours, so t represents the number of hours.
your rate of growth per hour is equal to 5% / 100 = .05, so r = .05.


the formula becomes f = p * (1 + .05) ^ t


since 400 bacteria are initially present, then p = 400.


the formula becomes f = 400 * (1 + .05) ^ t


after one hour, t = 1 and the formula becomes f = 400 * (1 +.05) ^ 1 = 400 * 1.05 = 420.


after 4 hours, t = 4 and the formula becomes f = 400 * (1 + .05) ^ 4 = 400 * 1.05^4 = 486.2025.


let y = f and x = t and you can graph this equation as shown below.


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