Question

A drawer contains a dozen each of red,blue,green,ad white socks,all unmatched.Laura takes socks out at random in the dark.How many socks must laura take to be sure she has 2 pairs of white socks

Answer 1

40 socks

Explanation:

There are 48 socks in total inside the drawer. 2 pairs of white socks means four white socks. The worst possible scenario (however unlikely it is) is that Laura takes all of the red, blue and green socks before picking any white sock. From that point on, Laura has to pick four more socks in order to have two white pairs. In this scenario, there are 8 socks left in the drawer, all white. Therefore, the minimum number of socks that Laura must take to be sure that she has two pairs of white socks is:

`n=(12*4) - 8\\n=40\ socks`

She must take at least 40 socks.