In this workout, we're given 10 days of share price history for a business We're then told that a bid was announced in February around this time i.e around the dates that are given to us From this information, what is likely to be the unaffected share price? Well I need to look through these numbers to see if I can see any jumps in numbers So if we look at the opening prices, the opening price of February 2nd, 3rd and 4th are around 63 But thereafter they all jump to 87 So it seems to me that February the 5th could be a good starting point for our announcement date If we always have a look to the number of shares traded, it jumps from around 1 million up to 40-41 million Thereafter it goes down to 16 million, 7 million, 6 million, 5 million, 8 million, 5 million. But generally much higher than previously It seems reasonable for us to expect that the announcement date was February 5th If I want to find the unaffected share price then, it would seem reasonable to use that from February the 4th In general though, we do want to look broader than this period we've been given here We want to look at one day before, one month before and maybe 90 days before or 90 days average We want to look back further than just one day because there may have been rumours built into the price before announcement Ideally we want the share price prior to the rumour The real underlying share price. So you look back one month, 90 day average to try and get that price before the rumour happened