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Finding the Fourth Proportional to 1,389.70, 2,084.82 and 415.78

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Solution

The fourth proportional to 1,389.70, 2,084.82 and 415.78 is: 623.75

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,389.70 : 2,084.82 = 415.78 : x
  2. Step 2: Convert to fraction form
    1,389.70/2,084.82 = 415.78/x
  3. Step 3: Cross multiply
    1,389.70x = 2,084.82 × 415.78
  4. Step 4: Simplify right side
    1,389.70x = 866,826.46
  5. Step 5: Solve for x
    x = 866,826.46/1,389.70
  6. Step 6: Final answer
    x = 623.75

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.