I found myself book-less on an MRT ride and looked around for something to do. I chanced upon the 10% Power Savings Campaign one of which claims:

Standb power can add upto 10% of your bill. Switch off appliances at the power socket to save about $50* a year!
* based on electricity tariff of $0.2388 per unit KWh, assuming 35W of standby power in a given home.

Now, it stands to reason that 10% of my monthly bill equals about $4 of power savings ($50/12) per month. Does that mean my monthly bill is only $40?

In an other advertisement in the same train, they claim 10% of your monthly bill can be saved by setting the temperature on the air-con 2 degrees higher than usual which comes to $50 per month. So now, my monthly bill equals $500!

I like maths, and am annoyed when people disregard maths just for the sake of a "10%" campaign. Would be a lot more effective if you give me the real statistics, instead of a fake 10% number.