Use the display of data to find the standard deviation

Abby is preparing fruit punch for her party. she starts with a bowl filled with liquid that has 1/2 fruit juice and 1/2 sprite, but she decides it's too fruity. so she pours out 1/4 of the liquid, and then fills the bowl up again with sprite. what fraction of the punch is now sprite?

Table which ratio is equivalent to 3: 7? 6: 7 3: 21 24: 56 15: 30

15 and 14.7 are 1 apart, so 15 – 14.7 must be 1.