The visa officers will want to satisfy themselves that this is your money and has not been borrowed. If you provide only a letter giving the total balance this may not (probably won't, in fact) satisfy them, and they may ask for at least 3 months statements.
Where are you getting this money from? If you're intending to borrow the money and pretend it belongs to you, then this is not allowed and you should expect to have your case refused. The ministerial instructions clearly state that the money must belong to you and cannot be borrowed, and I strongly suggest you don't try to lie to CHC.
If the money is genuinely yours and is from the sale of an asset or from another account, then you just need to prove the source of the funds. Send 3 months bank statements and then also show the source of the funds (receipts from sales or other account statements etc) to prove where the large deposit came from.
Wayne.