Answer:
3072
Explanation:
The number of cells is initially 3 and is multiplied by 2 every time t increases by 1/2 hour. This means the exponential function describing the number of cells can be written ...
y = (initial value) × (growth factor)^(t/(growth period)
y = 3 × (2^(t/(1/2)) = 3×2^(2t)
After 5 hours, the number of cells will be ...
y = 3×2^(2·5) = 3×2^10 = 3×1024
y = 3072
There are 3072 cells in 5 hours.
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Additional comment
The function could be simplified to ...
y = 3×4^t