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Finding the Fourth Proportional to 791.70, 1,187.55 and 645.90

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Solution

The fourth proportional to 791.70, 1,187.55 and 645.90 is: 968.85

Step by Step Solution

  1. Step 1: Write the proportion equation
    791.70 : 1,187.55 = 645.90 : x
  2. Step 2: Convert to fraction form
    791.70/1,187.55 = 645.90/x
  3. Step 3: Cross multiply
    791.70x = 1,187.55 × 645.90
  4. Step 4: Simplify right side
    791.70x = 767,038.55
  5. Step 5: Solve for x
    x = 767,038.55/791.70
  6. Step 6: Final answer
    x = 968.85

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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.