Take the tour ×  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.  share|improve this
question do you know the equation for exponential growth? – 
yiyi May 13 '12 at 17:11 In other words, it doubles every hour.
That should get you 3:00 PM easily. –  Michael Hardy May 13 '12
at 17:33 add comment  1 Answer   (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  share|improve this answer
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