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Finding the Fourth Proportional to 991.85, 1,489.39 and 415.13

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Solution

The fourth proportional to 991.85, 1,489.39 and 415.13 is: 623.37

Step by Step Solution

  1. Step 1: Write the proportion equation
    991.85 : 1,489.39 = 415.13 : x
  2. Step 2: Convert to fraction form
    991.85/1,489.39 = 415.13/x
  3. Step 3: Cross multiply
    991.85x = 1,489.39 × 415.13
  4. Step 4: Simplify right side
    991.85x = 618,281.99
  5. Step 5: Solve for x
    x = 618,281.99/991.85
  6. Step 6: Final answer
    x = 623.37

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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.