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Finding the Fourth Proportional to 619.81, 855.18 and 420.66

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Solution

The fourth proportional to 619.81, 855.18 and 420.66 is: 580.41

Step by Step Solution

  1. Step 1: Write the proportion equation
    619.81 : 855.18 = 420.66 : x
  2. Step 2: Convert to fraction form
    619.81/855.18 = 420.66/x
  3. Step 3: Cross multiply
    619.81x = 855.18 × 420.66
  4. Step 4: Simplify right side
    619.81x = 359,740.02
  5. Step 5: Solve for x
    x = 359,740.02/619.81
  6. Step 6: Final answer
    x = 580.41

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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.