Question

A certain colony of bacteria triples in length every 10min. Its length is now 1 millimeter. how long will it be in 40min?

(show work please! and in a 6th grader form)

Answer 1

Think of it this way. Every ten minutes, its length is multiplied by 3.

After 10 minutes, it will be 3 ml long.
After 20 minutes, it will be 9 ml long.
After 30 minutes, it will be 27 ml long.
After 40 minutes, it will be 81ml long.

In other words, 1x3x3x3x3=81

Answer 2

Bacteria length = 1mm

It will triple four times by 40 min.

This can be shown as 3 to the power of 4; 3⁴ = 81

Original length * growth factor = final length

1 mm * 81 = final length

81 = final length

After 40 mins, the bacteria colony will be 81 mm in length.