The rate of output per worker (or group of workers) per unit time is called

The correct answer is labour productivity.
Labour productivity refers to the rate at which output is produced by a worker or a group of workers in a given amount of time. It measures how efficiently and effectively workers are using their skills, time, and resources to produce goods or services.
To understand this concept, let's imagine a scenario where we have two workers producing bicycles. Worker A is able to produce 5 complete bicycles in one hour, while Worker B can only produce 3 complete bicycles in the same amount of time.
In this case, Worker A has a higher labour productivity because they are able to produce more output (bicycles) per unit of time (one hour) compared to Worker B.
Labour productivity is an essential measure for companies and economies because it directly impacts their profitability and competitiveness. Higher labour productivity means that more goods or services can be produced using the same amount of resources or in less time. This leads to lower costs per unit and can result in higher profits or the ability to lower prices for customers.
In summary, labour productivity is a measure of how efficiently workers are producing goods or services and is calculated by dividing the total output by the number of workers or the amount of time it took to produce that output.