## To find how many defective watches we would expect out of a total of 10,500, we need to use proportion.

Proportion of defective watches in the sample = 3/400 = 0.0075

We can use this proportion to estimate the number of defective watches in the entire population:

Expected number of defective watches = Proportion of defective watches x Total number of watches

Expected number of defective watches = 0.0075 x 10,500

Expected number of defective watches = 79

Therefore, based on the sample data, we would expect approximately 79 out of 10,500 watches to be defective.