Answer:
92
Step-by-step explanation:
Given
Scores: 85, 78, 81
Required
Determine the least score in 4th subject is average must be at least 84
To solve this, we'll make use of Mean formula.
Mean = Sum of observations/Number of observations
We have that; Average = 84
Number of subjects = 4
Let the 4th subject be represented by F;
So, the sum of the four Subjects is:
Sum = 85 + 78 + 81 + F
Sum = 244 + F
Substitute these values in the above formula.
84 = ¼(244 + F)
Multiply both sides by 4
4 * 84 = 4 * ¼(244 + F)
336 = 244 + F
Subtract 244 from both sides
336 - 244 = 244 - 244 + F
92 = F
F = 92
To have an average of at least 84, Su's score must be atleast 92
