The sum of the points of all the workers at a specific time is called the efficiency at that time, then at which of the following times of the day was the efficiency the lowest on September $$30^{th}$$

Let us fill in the points received by each worker by management at each time.

We know A = -2 : B = 5; C = 1 ; D = 0; E = 4; F = -3; G = 4

Take the total points received by each worker on 30th September and the total points received by all workers combined at a particular time.

The sum of the points of all the workers at a specific time is called the efficiency at that time, then at which of the following times of the
day was the efficiency the lowest on September $$30^{th}$$.
From the table we know that
At 10:30, efficiency = 15
At 4:30 or 16:30, efficiency = 19
At 3:30 or 15:30, efficiency = 0
At 2:30 or 14:30, efficiency = 6
Therefore, it is the lowest at 3:30.