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Finding the Fourth Proportional to 898.12, 1,239.28 and 499.78

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Solution

The fourth proportional to 898.12, 1,239.28 and 499.78 is: 689.63

Step by Step Solution

  1. Step 1: Write the proportion equation
    898.12 : 1,239.28 = 499.78 : x
  2. Step 2: Convert to fraction form
    898.12/1,239.28 = 499.78/x
  3. Step 3: Cross multiply
    898.12x = 1,239.28 × 499.78
  4. Step 4: Simplify right side
    898.12x = 619,367.36
  5. Step 5: Solve for x
    x = 619,367.36/898.12
  6. Step 6: Final answer
    x = 689.63

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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.