Question 1155286
68 means 1 sd on each side included.  So that would be 24-4 and 24+4 or interval (20, 28) 
For 95 it is 2 sd s and that would be (16, 32) The percentage below 16 if 2.5%, since the remaining 5% is split above 32 and below 16. ANSWER
For 99.7 it is 3 sd s and that would be (12, 36)