Question 552156
Harold calculated the mean of 5 numbers to be 68. 
Let n = sum of the 5 numbers
{{{n/5}}} = 68
n = 5*68
n = 340
Then he found that he made an error and had written 70 for one of the numbers when he should have written 80.
This raises n by 10, 350 is the correct sum
{{{350/5}}} = 70 is the correct mean