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Finding the Fourth Proportional to 1,389.85, 2,086.10 and 513.20

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Solution

The fourth proportional to 1,389.85, 2,086.10 and 513.20 is: 770.29

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,389.85 : 2,086.10 = 513.20 : x
  2. Step 2: Convert to fraction form
    1,389.85/2,086.10 = 513.20/x
  3. Step 3: Cross multiply
    1,389.85x = 2,086.10 × 513.20
  4. Step 4: Simplify right side
    1,389.85x = 1,070,579.36
  5. Step 5: Solve for x
    x = 1,070,579.36/1,389.85
  6. Step 6: Final answer
    x = 770.29

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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.