Can anybody explain for me Question 17 Predesign NCARB 3.1 . How they calculate the width of the sliding door to be 5' ?

Here is the link to NCARB 3.1

http://www.ironwarrior.org/ARE/_NCARB_Software/3_1/multiplechoice_31.pdf

Here is how I calculated:

-Living room/Dining Area 313SF ( The rest of the floor area looks to me 1/3 of the Living room/Dining ) so Floor area should be 313/2=156.5 x 3= 469.5

-5% of 469.5 = 23.47

-ventilation area = W x H, So 23.47=6.6 x X. X=3.5' The NCARB answer is 5'.

- Ventilation area should be half of the bypassing sliding door so the sliding door should be 3.5 x 2 = 7. The NCARB answer is 5'.