Solving Jan 2012 Edexcel S2, I encountered a few problems. Luckily, i had no problems with hypo and hopefully won't anymore. However, i encountered a problem simplifying k^2-k-1 = (1-root5)=2
I might be missing something stupid, but could someone help on that.
The time in minutes that Elaine takes to checkout at her local supermarket follows a
continuous uniform distribution defined over the interval [3, 9].
Given that Elaine has already spent 4 minutes at the checkout,
(d) find the probability that she will take a total of less than 6 minutes to checkout.
I seem to be getting stuck at these type of sums, I've seen the answer, but I need to know how it's coming.