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# C4 Exponential Growth- need help pls!! watch

1. Q) The number of bacteria, N, in a colony is such that the hourly rate of increase of N is equal to four times the number of bacteria present. Initially there are 200 bacteria present. Use the results from (a) to find the time taken for the number of bacteria to grow up to 700, giving your answer to the nearest minute.

From the previous part I was asked to show that N=200e^4t. The answer in the textbook is 19 minutes, but I just can't seem to get anywhere near that... I've tried substituting 700 into the above equation but I get a really small number for t... please can someone help, thanks.
2. (Original post by jordanwu)
Q) The number of bacteria, N, in a colony is such that the hourly rate of increase of N is equal to four times the number of bacteria present. Initially there are 200 bacteria present. Use the results from (a) to find the time taken for the number of bacteria to grow up to 700, giving your answer to the nearest minute.

From the previous part I was asked to show that N=200e^4t. The answer in the textbook is 19 minutes, but I just can't seem to get anywhere near that... I've tried substituting 700 into the above equation but I get a really small number for t... please can someone help, thanks.
Well the time is in hours, so you probably just need to convert. I get 18.79 minutes
3. (Original post by 13 1 20 8 42)
Well the time is in hours, so you probably just need to convert. I get 18.79 minutes
Omg I'm such an idiot haha only just realised I had to convert hours into minutes, thank you!

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