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Finding the Fourth Proportional to 720.14, 991.85 and 621.72

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Solution

The fourth proportional to 720.14, 991.85 and 621.72 is: 856.30

Step by Step Solution

  1. Step 1: Write the proportion equation
    720.14 : 991.85 = 621.72 : x
  2. Step 2: Convert to fraction form
    720.14/991.85 = 621.72/x
  3. Step 3: Cross multiply
    720.14x = 991.85 × 621.72
  4. Step 4: Simplify right side
    720.14x = 616,649.87
  5. Step 5: Solve for x
    x = 616,649.87/720.14
  6. Step 6: Final answer
    x = 856.30

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.