Question 947142
To calculate the new mean,
{{{A[1]=T[1]/24=82}}}
{{{T[1]=1968}}}
So then,
{{{A[2]=(1968+86)/25=82.16}}}
Since the median was 81.5, it's the average of the highest score in the lowest 12 and the lowest score in the highest 12. The lowest possible score in the highest 12 would have been 82. This score became the lowest possible median when the 86 was scored. 
So then,
{{{D=abs(82.16-82)}}}
{{{D=0.16}}}