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Finding the Fourth Proportional to 1,389.88, 2,085.09 and 620.38

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Solution

The fourth proportional to 1,389.88, 2,085.09 and 620.38 is: 930.68

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,389.88 : 2,085.09 = 620.38 : x
  2. Step 2: Convert to fraction form
    1,389.88/2,085.09 = 620.38/x
  3. Step 3: Cross multiply
    1,389.88x = 2,085.09 × 620.38
  4. Step 4: Simplify right side
    1,389.88x = 1,293,534.61
  5. Step 5: Solve for x
    x = 1,293,534.61/1,389.88
  6. Step 6: Final answer
    x = 930.68

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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.