2 persons working 2 hours a day for each of 2 days produce 2 article’s. 2 persons working 2 hours a day for each of 1 day produce
2
2
= 1 article. 2 persons working 1 hour a day for each of 1 day produce
1
2
article. 1 person working 1 hour a day for each of 1 day produce
1
2×2
=
1
4
article. 4 persons working 1 hour for 4 days for each of 1 day produce
1
4
×4 article. 4 persons working 4 hours for day produce 1 × 4 = 4 articles. 4 persons working 4 hours for 4 days for each of 4 days produce 4 × 4 = 16 articles.