Which is bigger 471 or 468

471 is bigger than 468.

468 is a lower number than 471. If it is lower, then it is not the biggest. 
468 is close to 471, but it is not more than it. 
Look at them both just with their second number. 060 and 070. 6 is lower than 7, and 7 is bigger than 6, meaning that the answer is 471. If you were looking for the lower number, it would be 468.

a) The growth of bacteria at nth hour is :

b) At the end of the fourth hour, there are 81 stands of the bacteria    

    present.

Step-by-step explanation:

The number of initial bacteria in the dish = 3 strands

Rate at which bacteria multiply = 3 times every hour

So, the general form which represents the growth

As it multiplies three times every hour, so at nth hour:

The growth of bacteria at nth hour is :

Now, at n = 4, the growth of the bacteria is  

= 3 x 3 x 3 x 3

⇒ = 81

So, at the end of the fourth hour, there are 81 stands of the bacteria present.