Answer:
92
Step-by-step explanation:
Let x be the additional number.
Therefore Reuben score will be
70, 75, 83, 80 and x.
From the question, we were told that the next mark will make Reuben to have an average of 80. This can be illustrated below:
Mean = sum of marks / numbers of mark
Mean = 80
Number of mark = 5
80 = (70 + 75 + 83 + 80 + x) / 5
80 = (308 + x) / 5
Cross multiply
308 + x = 80 x 5
308 + x = 400
Collect like terms
x = 400 — 308
x = 92
Reuben must score at least 92
