Jan 1 100,000 shares issued (1st issue)
Apr 1 20,000 shares issued
Jul 1 10% stock dividend declared
Oct 1 10,000 shares purchased as Treasury stock
on Dec 31, the weight average number of shares outstanding is?

my calculation is as follows
my answer is 118,500 but was told it was wrong !
Please help.

I need to hand in by Monday.

Thanks.

100,000 x 3months = 300,000
120,000 x 3months = 360,000
132,000 x 3months = 396,000
122,000 x 3months = 366,000
---------
1,422,000

1,422,000 / 12 = 118,500 shares

Your calculation is correct IF the shares issued pursuant to the stock dividend were in fact issued on Jul 1. Remember that "declared" doesn't = "issued"; maybe that's where the problem lies. However, there's no indication of when the shares were actually issued, at least in the question as posted. Check the background material.