Starting with 30 bacteria and doubling factor 2, the count after n hours is 30 x 2ⁿ. Thus, after 2 hours there are 120, after 4 hours 480 and after n hours 30 x 2ⁿ.
The number of bacteria in a certain culture doubles every hour. If there were 30 bacteria present in the culture originally, how many bacteria will be present at the end of the 2nd hour, 4th hour and nth hour?
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The initial bacteria count is 30 and the population doubles each hour.
This forms a geometric progression where the count at the end of each hour is:
After 1 hour: 30 x 2 = 60
After 2 hours: 30 x 2² = 30 x 4 = 120
After 3 hours: 30 x 2³ = 240
After 4 hours: 30 x 2⁴ = 30 x 16 = 480
In general, after n hours:
Number of bacteria = 30 x 2ⁿ.
Hence, the counts are 120, 480 and 30 x 2ⁿ bacteria respectively.
For more NCERT Solutions of Class 9 Ganita Manjari Chapter 8 Predicting What Comes Next: Exploring Sequences and Progressions Question Answer (2026-27)
https://www.tiwariacademy.com/ncert-solutions/class-9/maths/ganita-manjari-chapter-8/