# Risk Management portfolio: how to calculate annualized PD and STDEV?

I'm doing a Risk Management exercise on Excel and I need help, I'm lost. I'm analysing a company's portfolio divided into different tabs. In one of the tabs, called "Pool PD", there is a table similar to this (I'm only showing the first 10 months out of the 57 to give an example):

Month ending Total Current 1-30 days 31-60 days 61-90 days 91-120 days 121-150 days 151-180 days Over 180 days Default Ratio
Nov/95 60.200,00 60.200,00 - - - - - - - 0.00%
Dec/95 545.734,21 545.734,21 - - - - - - - 0.00%
Jan/96 22.448.554,71 22.448.554,71 - - - - - - - 0.00%
Feb/96 54.222.786,35 54.222.786,35 - - - - - - - 0.00%
Mar/96 70.972.975,98 70.972.975,98 - - - - - - - 0.00%
Apr/96 113.483.342,76 113.444.801,09 38.541,68 - - - - - - 0.00%
May/96 174.161.633,78 174.123.092,10 - 38.541,68 - - - - - 0.00%
Jun/96 268.885.255,68 268.600.001,98 246.712,03 - 38.541,68 - - - - 0.00%
Jul/96 393.962.717,15 393.518.651,58 367.190,55 38.333,35 - 38.541,68 - - - 0.01%
Aug/96 545.011.667,64 541.785.233,18 3.035.976,11 152.125,00 38.333,35 - - - - 0.00%

The last column, Default Ratio, they already give me the values by calculating `(91-120 days column) / (Total column)` for each row, so naturally all Default Ratios are 0.00%, except for July 96, which is 0.01%.

The exercise asks me to calculate:

1. Average Default Ratio (PD) - I did the average of all Default Ratios;
2. STDEV - I'm guessing I need to calculate the Standard Deviation of all Default Ratios, which I did as well;
3. Annualized PD;
4. Annualized STDEV.

Number 3 and 4 I don't know what formulas to use. I read some articles but I don't know which ones to apply to this case.

Any help would be appreciated, thank you!