Question

Item 10 A bacterial culture quadruples in size every hour. You begin observing the number of bacteria 3 hours after the culture is prepared. The amount y of bacteria x hours after the culture is prepared is represented by y=192(4x−3). When will there be 200,000 bacteria? Round your answer to the nearest hundredth. There will be 200,000 bacteria about hours after the culture is prepared.

Answer 1

Answer:

There will be 200 000 bacteria after 8 hours

Step-by-step explanation:

The crop quadruples every hour.

x represents the number of hours that pass after preparing the crop

y represents the number of bacteria after x hours.

The equation for y in function of x  3 hours after observing the crop is:

$y = 192(4^{x - 3})$

We want to know after how long there will be 200 000 bacteria.

Then we make y = 200 000 and clear x.

$200\ 000 = 192(4^{x - 3})\\\\log(200\ 000) = log(192(4^{x-3}))\\\\log(200\ 000) = log(192) + log(4 ^{x-3})\\\\log(200\ 000) - log(192) = (x-3)log(4)\\\\\frac{log(200\ 000) - log(192)}{log(4)} = (x-3)\\\\x = 3 + \frac{log(200\ 000) - log(192)}{log(4)}\\\\x = 8\ hours$