Quirky VAR calculation

Anyone notice this from the CFAI text (problem 10c, reading 37), converting monthly standard deviation to weekly. Ignorantly i thought it just divide the monthly return by 4 and the std by sqrt(4). Nope, monthly return * 12 then divide by 52. std deviation multiply by sqrt(12) then divide by sqrt(52). just a heads up - these are the type of questions that you think you nail. good luck to all.

Yep - thats b/c there is like 4.33 weeks per month and that calc gets you back there. 52/12 = 4.33 or 31/7 =4.42 30/7 = 4.28 so 4.33 works