Question

how to solve word problem of unitary method?​

Answer 1

Solved problems on unitary method using inverse variation:

1. 12 typists working for 4 hours to type a book in 18 days. In how many days 4 typists will work for 8 hours to type same book?

Solution:

This is a situation of indirect variation.

12 typists working for 4 hours type a book in 18 days

1 typist working for 4 hours types a book in 18 × 12 days.

1 typist working for 1 hour types a book in 18 × 12 × 4 days.

4 typists working for 1 hour type a book in (18 × 12 × 4)/4

4 typists working for 8 hours type a book in (18 × 12 × 4)/(4 × 8) days.

Therefore, 4 typists working for 8 hours type a book in 27 days.