Question 974635
At  the start of an experiment, Lucy had 4000 bacteria cells in a culture. The number of bacteria double each hour.

The number of bacteria after x hours can be found using formula B =4000(2x).
How many hours have passed if 2,048,000 bacteria cells are present? 
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I think you mean B =4000*2^x  Use ^ (Shift 6) for exponents.
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B =4000*2^x = 2048000
2^x = 512
2^x = 2^9
x = 9 hours
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If you don't recognize that 512 = 2^9:
2^x = 512
x*log(2) = log(512)
x = log(512)/log(2)
x = 9