Need Help - Question on TSSM 2011 Exam 2 (Probability)

[xXjAmEZXx]

Hey guys! I just need assistance with a question that I may or may not be interpreting.

Question 2
Jealeen and Chris have clients who buy coloured light globes and candles. If they buy coloured light globes on day, the probability they will buy coloured light globes the next day is m. If they buy candles one day, the probability they will buy coloured light globes is m-0.3.

dii
On this day (m = 0.71) a customer bought three items, either coloured light globes or candles. Chris knows that the first item is a candle. FInd the expected number of these three items that will be coloured light globes, correct to three decimal places.


I got this wrong and checked in the solutions that apparently the transitional matrix used for workings is [m, 1-(m-0.3);1-m, m-0.3] but i believe it is [m, m-0.3; 1-m, 1-(m-0.3)]

Can anyone clarify or explain why I am wrong?


Thanks

[BlueSky_3]

Yeah you're not wrong their solution is wrong! Imagine having this for a trial exam in school, where you're working through it and suddenly realise that you must of had done something wrong. Well that's exactly what happened to me at my school