Answer:
350 lightbulbs
Step-by-step explanation:
First find the number of batches made.
20,000 divided by 400 = 50
This means that there are 50 batches in which 7 light bulbs will be selected at random to be inspected.
We can multiply the number of batches to the lightbulbs being inspected.
50 times 7 = 350
Therefore, 350 lightbulbs will be inspected.
Please tell me if I am incorrect :)