The answer to the following can be determined by using a direct proportion:
If 12 books cost $120, what is the cost for 6 books at the same cost per book?
Solution:
(books) 12/6 = (cost)$120/?
Cross multiply:
12 X ? = 6 X 120
? = $60.00
Can an indirect proportion be used to determine the same answer if some changes are made to some of the information? The solution requires a unit which is the reciprocal of one in the original question.
If 12 books cost $120, what is the cost for 6 books at the same cost per book?
Solution:
(books) 12/6 = (cost)$120/?
Cross multiply:
12 X ? = 6 X 120
? = $60.00
Can an indirect proportion be used to determine the same answer if some changes are made to some of the information? The solution requires a unit which is the reciprocal of one in the original question.