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Finding the Fourth Proportional to 771.38, 1,155.72 and 642.21

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Solution

The fourth proportional to 771.38, 1,155.72 and 642.21 is: 962.19

Step by Step Solution

  1. Step 1: Write the proportion equation
    771.38 : 1,155.72 = 642.21 : x
  2. Step 2: Convert to fraction form
    771.38/1,155.72 = 642.21/x
  3. Step 3: Cross multiply
    771.38x = 1,155.72 × 642.21
  4. Step 4: Simplify right side
    771.38x = 742,211.03
  5. Step 5: Solve for x
    x = 742,211.03/771.38
  6. Step 6: Final answer
    x = 962.19

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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.