The growth control factor is 4^(t/5). This can also be written 2^(2t/5)=2^0.4t.
The function f(t)=p₀2^(0.4t) where p₀=25 the initial number of bacteria.
When t=1, f(1)=1.32p₀ so the daily growth rate is 1.32 approx (a).
(b) f(t)=p₀2^(0.4t) where p₀=25 the initial number of bacteria.
(c) f(7)=25×2^2.8=174.