Here is a practical problem from a factory. There are illiterate workers who can not identify digits and do not know in which order they occur. They are supposed to fill cans with a certain weight of a given material. With a beam balance this is easy since a worker can place the required weight in one pan and keep pouring the material in another pan as long as the beam doesn't appear to be balanced. However, this factory uses digital weighing scales. What do you think is the easiest way to train the workers to do their job with a digital weighing scale apart from teaching them how to count or altering the digital weighing scale?

Note that the workers may be asked to fill a can with 3.1 kg of material, i.e. decimal fractions may be involved.

Update: Prunthaban's solution in the comments was successfully implemented at OCL India Limited, Rajgangpur. Thanks, Prunthaban.

## 7 comments

## MS Vivek Chaitanya said:

With bean balance also it is difficult because the worker may not know what denominations of weights to put in one pan.

It is much easy with Digital scale because it shows the numbers. You can print all the weights on a paper, give it to them and ask them to put the material until the number in the paper matches the number in the meter.

## Susam Pal said:

Vivek, In a beam balance, once a supervisor tells them which weights to use, their job is easy. With a digital scale, it is not as easy as it seems to you. Let us say a worker is supposed to pour 4.3 kg of material. He pours a little too much material and the scale shoots to 6.2 kg. Now, he doesn't know whether he should keep pouring more material or remove material.

## Veera said:

the digital balance has to be designed such a way that a weight can be preset (For example, 3.1). So when the worker fill a can and the total weight reaches the preset value the digital can alert the worker either by showing a green light or beeping. The worker must be able to notice this alert and he can stop filling more.

## srinivasang87 said:

Sell the digital scale and get an analog one :)

## Prunthaban said:

Here is my solution: Most digital scales have a button called 'Set to 0'. So let us say I want the people to have 4.3 Kgs. I keep 4.3 Kg weight on the scale and press 'Set to 0'. Now after removing the weight it starts showing "-4.3". The worker only needs to pour until it reaches 0.00 (He just needs to know 0 to do this). To know whether to pour more or remove from the balance he just needs to look at the '-' sign. If it is there keep pouring, else remove :-) So he can achieve the task with remembering "0.00.." and "-" signs.

## Indhu said:

@Prunthaban: That was a cool one!

## Susam Pal said:

Prunthaban,

Your solution solved the problem. I have updated this post to mention this. Thanks for the solution.