Process costing

Hi

1) W&B Ltd produce a breakfast cereal that involves several processes. At each stage in the process, ingredients are added, until the final stage of production when the cereal is boxed up ready to be sold.
In Process 2, W&B Ltd have initiated a quality control inspection. This inspection takes place before any new ingredients are added into Process 2. The inspection is expected to yield a normal losses of 5% of the input from Process 1. These losses are sold at $1 per kg.
Following information is for Process 2 for the period just ended:

Units $

Transfer from Process 1 – 500 kg 750
Material added in Process 2 – 300 kg 300
Labour 200 hrs 800
Overheads – –
Actual output 750 kg –

Prepare the process account, abnormal loss and gain account and scrap account for Process 2 for the period just Ended.

2) X uses process costing. In process 3 the normal loss is 4% of total input. Last period the input from Process 2 was 8,500 kg and additional material of 4,250 kg was added to process 3.

Actual output to finished goods was 12,700 kg
there was no opening or closing WIP in the period.

What was the abnormal gain or loss in kg for period 3 ?

My question is about the concept behind these calculations. I don’t get it fully these two seem similar but the calculation is different.

In the first task, they calculated NORMAL LOSS like this: Normal Loss = 5% of transfer from Process 1 = 500kg X 0.05 (5%)= 25 kg
which gives us expected output: 800 input – 25 loss = 775 expected output

But in the second task, they calculated differently. First of all, they summed up Input from process 2 and additional material 8,500 kg +4,250=12750 and then deducted normal loss.

Can you explain why is that so?

thanks in advance