Suppose the population of a certain bacteria in a laboratory sample is 100.if it doubles in the population every 5hrs,what is the qrow rate?how many bacteria will there be in 3 days?

2 Answers
Jun 26, 2018

Let tt be the time in hours, P_oPo the initial population so P=P_o e^{kt}P=Poekt is the population at tt. We're given 2=e^{5k}2=e5k so k=1/5 ln 2k=15ln2. We're asked for PP at t=3(24)=72t=3(24)=72 which is

P= 100 e^{(1/5 ln 2)(72)} = 1638400 cdot 2^(2/5) approx 2161881P=100e(15ln2)(72)=16384002252161881

Jun 26, 2018

Growth rate is 0.1386290.138629 and bacteria population after
7272 hours will be 21618822161882

Explanation:

B_0= 100 , B_5=200 , B_72= ? , k = ?B0=100,B5=200,B72=?,k=?

B_t = B_0*e^(kt); k , t Bt=B0ekt;k,t are rate of growth and time in hours.

B_5 = B_0*e^(kt) or 200 =100 *e^(k*5)B5=B0ektor200=100ek5 or

e^(5 k)= 200/100 or e^(5 k)= 2e5k=200100ore5k=2 . Taking natural log on both

sides we get , 5*k*ln (e)= ln (2) or k = ln(2)/5 ; [ln (e)=1]5kln(e)=ln(2)ork=ln(2)5;[ln(e)=1]

:.k~~0.138629. Growth rate is 0.138629 and growth

equation is B_t = B_0*e^(0.138629*t)

Bacteria population after 72 hours will be

B_72 = 100*e^(0.138629*72)=2161882 [Ans]