How to Solve Hannah’s Sweets GCSE Math Problem on Probability
Friday, June 5th, 2015
Social Media is at it again. And this time it is a simple probability question. It is pretty basic in nature. The story in the question takes a turn to probability towards the end which is probably what surprised a lot of people. Well, decide for yourself.
The actual question
There are n sweets in a bag. 6 of the sweets are orange. The rest of the sweets are yellow.
Hannah takes a random sweet from the bag. She eats the sweet.
Hannah then takes at random another sweet from the bag. She eats the sweet.
The probability that Hannah eats two orange sweets is 1/3.
Show that n² – n – 90 = 0.
Video Solution to Hannah’s Sweets GCSE Math Problem on Probability
If you want a quick and dirty solution (basically something that can come in a tweet):
(6/n)*(5/(n-1)) = 1/3
=> 6*5*3 = n(n-1)
=> 90 = n² – n
=> n² – n – 90 = 0
Hope you enjoyed it and learnt from it. Do share it with your friends on facebook
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