The bacteria in a culture grows by 10% in the first hour, decreases by

1.	The bacteria in a culture grows by 10% in the first hour, decreases by 10% in the second hour and again increases by 10% in the third hour. If the original count of the bacteria in a sample is 10000, find the bacteria count at the end of 3 hours. (a) 13310 (b) 10890 (c) 10990 (d) 11000
Answer» (b) 10890 Bacteria count after 3 years = 10000\(\big(1+\frac{10}{100}\big)\)\(\big(1-\frac{10}{100}\big)\)\(\big(1+\frac{10}{100}\big)\) = 10000 x \(\frac{11}{10}\)x \(\frac{9}{10}\)x \(\frac{11}{10}\) = 10890.

The bacteria in a culture grows by 10% in the first hour, decreases by 10% in the second hour and again increases by 10% in the third hour. If the original count of the bacteria in a sample is 10000, find the bacteria count at the end of 3 hours. (a) 13310 (b) 10890 (c) 10990 (d) 11000

Answer»

(b) 10890

Bacteria count after 3 years

= 10000\(\big(1+\frac{10}{100}\big)\)\(\big(1-\frac{10}{100}\big)\)\(\big(1+\frac{10}{100}\big)\)

= 10000 x \(\frac{11}{10}\)x \(\frac{9}{10}\)x \(\frac{11}{10}\) = 10890.