The expected outcome would be 6 black/ 12 total = 6/12
The actual outcome was 14 out of 24 = 14/24, reduces to 7/12
Percent error = ( actual - expected) / expected x 100
Percent error = (7/12 - 6/12) / 6/12 x 100
Percent error = 1/12 / 6/12 x 100
Percent error = 1/12 x 12/6 x 100
= 12/72 x 100
= 1/6 x 100
= 16.67%