On a test that has a normal distribution, a score of 80 falls three standard deviations above the mean, and a score of 56 falls one standard deviation below the mean. Determine the mean of this test.

Long division setup showing an incomplete calculation. 12 is in the divisor, 6839 is in the dividend, and 5 hundreds and 6 tens is written in the quotient. 6000 is subtracted from 6839 to give 839. an unknown value represented by a box is being subtracted from 839. what number should be placed in the box to complete the division calculation?