The figures "estimated btc/usd transaction volume" on blockchain.info are pretty much wild guesses.

I just took 2 transactions there randomly for illustration.
Example 1: https://blockchain.info/tx/0b792182e993388448c925359cf05b1f74f2dd6cce6fcded42a65618e8d86b23
How much has been transacted? 0.999 btc? 1 btc? 7 btc? or all 7.999 btc?

Example 2: https://blockchain.info/tx/3835d244dd73a3ab6d1b4466874703364c234d703b5c161d16fd97361bbcd582
Which one is the change? 1.73070266? or 0.57440711?