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Algebra Ratios and Proportions Practice Questions (page 2)

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Updated on Oct 3, 2011

Practice 2

  1. The number of blue pens is unknown, so represent that number with x.

    There are 9 more black pens than blue pens, which means that the number of black pens is equal to x + 9. The ratio of black pens to blue pens is 7:4, or .

    The ratio of actual black pens to actual blue pens is (x + 9):x, or .

    These ratios are equal. Write a proportion and solve for x:

    7x = 4x + 36

    3x = 36

    x = 12

    There are 12 blue pens in the box.

  2. The number of fiction books is unknown, so represent that number with x.

    There are 4 more fiction books than nonfiction books, which means that the number of nonfiction books is equal to x. – 4. The ratio of fiction books to nonfiction books is 6:5, or . The ratio of actual fiction books to actual nonfiction books is x:(x – 4), or .

    These ratios are equal. Write a proportion and solve for x:

    5x = 6x –24

    x = –24

    x = 24

    There are 24 fiction books on the shelf.

  3. The number of parents is unknown, so represent that number with x.

    The number of students is 6 more than 4 times the number of parents, which means that the number of students is equal to 4x + 6. The ratio of parents to students is 2:9, or . The ratio of actual parents to actual students is x:(4x + 6), or .

    These ratios are equal. Write a proportion and solve for x:

    9x = 8x + 12

    x = 12

    Therefore, 12 parents went on the trip.

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