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Finding the Fourth Proportional to 1,398.21, 1,929.20 and 808.71

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Solution

The fourth proportional to 1,398.21, 1,929.20 and 808.71 is: 1,115.83

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,398.21 : 1,929.20 = 808.71 : x
  2. Step 2: Convert to fraction form
    1,398.21/1,929.20 = 808.71/x
  3. Step 3: Cross multiply
    1,398.21x = 1,929.20 × 808.71
  4. Step 4: Simplify right side
    1,398.21x = 1,560,159.29
  5. Step 5: Solve for x
    x = 1,560,159.29/1,398.21
  6. Step 6: Final answer
    x = 1,115.83

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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.