How to formulate exponential growth?

Question

Here's my question:

A rumour spreads exponentially through a college. 100 people have heard it by noon, 200 by 1pm. How many people have heard it

a) by 3pm b) 12.30pm c)1.45pm

thanks in advance.

In other words, it doubles every hour. That should get you 3:00 PM easily. — Michael Hardy, May 13 '12 at 17:33

score 3 · Answer 1 · answered May 13 '12 at 10:06

3

Hints:

(a) the number doubles every hour, i.e. multiplies by $2$

(b) the number multiplies by $\sqrt{2}$ every half-hour

(c) the number multiplies by $2^\frac14$ every quarter of an hour

answered May 13 '12 at 10:06

Henry

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How to formulate exponential growth?

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