Final answer:
The trader started with 2 1/2 crates of eggs, sold 42, and then ordered enough to bring the total up to 2,163 eggs. After calculating, it was found that the trader ordered approximately 3.625 additional crates of eggs.
Step-by-step explanation:
The question requires determining the number of crates of eggs ordered by a trader after a friend bought some of the eggs.
First, we convert the quantity of 2 1/2 crates of eggs to a whole number by expressing it as an equivalent number of eggs. Since a crate typically contains 30 dozen eggs or 360 eggs, 2 1/2 crates contain 2.5 x 360 = 900 eggs.
After the friend bought 42 eggs, the trader is left with 900 - 42 = 858 eggs.
Next, we need to find out how many more crates were ordered to reach a total of 2,163 eggs. We subtract the number of eggs after the sale from the total to find the number of eggs ordered:
2,163 - 858 = 1,305 eggs
Finally, we divide this number by 360 to find the number of crates:
1,305 / 360 ≈ 3.625 crates
Therefore, the trader ordered approximately 3.625 crates of eggs to have a total of 2,163 eggs.