Practice with Proportions
Gives 3 numbers and asks for a fourth
Try the following problems:
Are the following true proportions?
Remember a proportion is 2 equal fractions. If you cross multiply the products are equal
Answer a NO
Answer b YES
Explanation In part a, the product of the means does not equal the product of the extremes. (10 does not equal 30) In part b, it does. (30=30)
Solve for x:
Gives 3 numbers and asks for a fourth.
Answer 28
Explanation Product of the means equals product of the extremes. 6x = 168 Divide both sides by 6. x = 28
Answer 4
Explanation Product of means equals product of extremes. 15x = 5x + 40 Subtract 5x from both sides. 10x = 40 x = 4
If 4 tickets to a show cost $9.00, find the cost of 14 tickets.
Answer $31.50
Be consistent--$ with $ and tickets with tickets
Explanation Let c = cost of the tickets 4/9 = 14/c 4c = 126 c = 31.5 c=$31.50
A house which is assessed for $10,000 pays $300 in taxes. What should the tax be on a house assessed at $15,500?
Answer $465
Be consistent--assessed with assessed and taxes with taxes
