A toolbox contains 3 sizes of Robertson screwdrivers, 4 sizes of Phillips screwdrivers, and 5 sizes of flat-head screwdrivers. If you randomly pull a screwdriver

Question

What are the odds against it being a flat- head screwdriver? Express as reduced ratio.

Answer 1

The total number of screwdrivers in the toolbox is 3 (Robertson) + 4 (Phillips) + 5 (flat-head) = 12.

The number of flat-head screwdrivers is 5.

The odds against pulling a flat-head screwdriver can be calculated as:
(Number of non-flat-head screwdrivers) / (Number of flat-head screwdrivers) = (3 + 4) / 5 = 7 / 5 = 1.4

Therefore, the odds against pulling a flat-head screwdriver are 7:5.