Eating Less Fat Reduces Analytical Skills

There was a packet of a snack product on our kitchen counter. The snack claims to have 30% less than regular crisps (Actually it uses the words potato chips, but I am still trying to use English and not American in this blog). In smaller print it then says that regular crisps have 10g of fat per oz, while these have 6g of fat per oz. Aside from the odd mixing of metric and non-metric measures, 6g is 40% less than 10g. The headline claim is thus wrong, but is understating the advantage; their marketers seem to be mathematically challenged.