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Finding the Fourth Proportional to 1,389.84, 2,085 and 415.84

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Solution

The fourth proportional to 1,389.84, 2,085 and 415.84 is: 623.83

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,389.84 : 2,085 = 415.84 : x
  2. Step 2: Convert to fraction form
    1,389.84/2,085 = 415.84/x
  3. Step 3: Cross multiply
    1,389.84x = 2,085 × 415.84
  4. Step 4: Simplify right side
    1,389.84x = 867,026.40
  5. Step 5: Solve for x
    x = 867,026.40/1,389.84
  6. Step 6: Final answer
    x = 623.83

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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.