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Finding the Fourth Proportional to 1,218.87, 1,681.50 and 721.17

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Solution

The fourth proportional to 1,218.87, 1,681.50 and 721.17 is: 994.89

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,218.87 : 1,681.50 = 721.17 : x
  2. Step 2: Convert to fraction form
    1,218.87/1,681.50 = 721.17/x
  3. Step 3: Cross multiply
    1,218.87x = 1,681.50 × 721.17
  4. Step 4: Simplify right side
    1,218.87x = 1,212,647.36
  5. Step 5: Solve for x
    x = 1,212,647.36/1,218.87
  6. Step 6: Final answer
    x = 994.89

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.