Page 156minutes (x) # of bacteria (y) Express in Exponents

0 1 1 = 1 1

20 2 2 = 21

40 4 4 = 2 X 2 = 22

60 (1 hour) 8 8 = 2 X 2 X 2 = 23

80  16  24100  32  25120 (2 hours)  64  26140  128  27160  256  28180 (3 hours)  512  29200  1024  210220  2048  211240 (4 hours)  4096  212260  8192  213280  16384  214300 (5 hours)  32768  215

½ pt for each column

1. Express the number of bacteria after 80 minute periods using exponents. __________

2. Express the number of bacteria after 120 minute periods using exponents. __________

3. Express the number of bacteria after 240 minute periods using exponents. __________

4. Express the number of bacteria after 300 minute periods using exponents. __________

5. Bacteria is said to reproduce “exponentially.” What might this mean?

 24

 26

 212

 215

 Every time the bacteria reproduce, the number doubles. 

½ pt for each

• Title – 1 pt• X axis (time) – ½ pt• Y axis (# bacteria) – ½ pt

0 40 80120

160200

240280

0

5000

10000

15000

20000

25000

30000

35000

Time (min)

# bacteria

6. Is the graph steady? If so, from when to when? 7. From what point(s) in time do you notice the graph

increasing slightly? 8. From what point(s) in time do you notice the graph begin to

increase sharply? 9. Based on this information, when is the rate of bacterial

growth fastest? 10. At 225 minutes, how many bacteria were on the kitchen

counter? 11. At 250 minutes, how many bacteria were on the kitchen

counter? 12. Explain what process you used to figure out your answers to

questions 8 and 9. 13. If you had 15,000 bacteria on the kitchen counter, for how

many minutes were the bacteria dividing on the counter?

Appears “steady” from 0 – 160, but population is doubling. 

160-220 min

220 – 300 min

Rate = # bacteria/time    ;     Fastest towards the end, although it doubles every time.

About 3,000 

Interpolating – We used the graph to estimate a valueBetween two known values. 

About 275 min

About 6,000