Question

the bacteria in a culture grows by 10 percent in the first hour decreases by 10 percent in the second hour and again increases by 10 percent in the third hour find the bacteria at the end of the third hour if the count was initially 20000

Answer 1

"Given: The bacteria in a culture grows by 10 percent in the first hour decreases by 10 percent in the second hour and again increases by 10 percent in the third hour.

To find: The bacteria at the end of the third hour if the count was initially 20000.

20000×10/100 =22000

22000- 22000×10/100 = 19800

19800+19800×10/100 = 21780

Therefore, answer 21780 bacteria are present at the end of the third hour."

Answer 2

Given bacteria count is 10000 at first hour it increases by 10% = 10000×10/100=1000 now bacteria count is 11000 at second hour it decreases by 10%=11000×10/100=1100 now bacteria count is 11000-1100 = again 10000 at third hour the count increases by 10%=10000×10/100=1000 now present bacteria count after three hours is 10000+1000 =11000.......