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Finding the Fourth Proportional to 840.56, 1,258.86 and 428.68

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Solution

The fourth proportional to 840.56, 1,258.86 and 428.68 is: 642.01

Step by Step Solution

  1. Step 1: Write the proportion equation
    840.56 : 1,258.86 = 428.68 : x
  2. Step 2: Convert to fraction form
    840.56/1,258.86 = 428.68/x
  3. Step 3: Cross multiply
    840.56x = 1,258.86 × 428.68
  4. Step 4: Simplify right side
    840.56x = 539,648.10
  5. Step 5: Solve for x
    x = 539,648.10/840.56
  6. Step 6: Final answer
    x = 642.01

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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.