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Finding the Fourth Proportional to 1,218.53, 1,680.88 and 721.09

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Solution

The fourth proportional to 1,218.53, 1,680.88 and 721.09 is: 994.70

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,218.53 : 1,680.88 = 721.09 : x
  2. Step 2: Convert to fraction form
    1,218.53/1,680.88 = 721.09/x
  3. Step 3: Cross multiply
    1,218.53x = 1,680.88 × 721.09
  4. Step 4: Simplify right side
    1,218.53x = 1,212,065.76
  5. Step 5: Solve for x
    x = 1,212,065.76/1,218.53
  6. Step 6: Final answer
    x = 994.70

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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.