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Finding the Fourth Proportional to 765.84, 1,056.42 and 485.60

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Solution

The fourth proportional to 765.84, 1,056.42 and 485.60 is: 669.85

Step by Step Solution

  1. Step 1: Write the proportion equation
    765.84 : 1,056.42 = 485.60 : x
  2. Step 2: Convert to fraction form
    765.84/1,056.42 = 485.60/x
  3. Step 3: Cross multiply
    765.84x = 1,056.42 × 485.60
  4. Step 4: Simplify right side
    765.84x = 512,997.55
  5. Step 5: Solve for x
    x = 512,997.55/765.84
  6. Step 6: Final answer
    x = 669.85

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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.