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Finding the Fourth Proportional to 765.43, 1,055.80 and 485.57

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Solution

The fourth proportional to 765.43, 1,055.80 and 485.57 is: 669.77

Step by Step Solution

  1. Step 1: Write the proportion equation
    765.43 : 1,055.80 = 485.57 : x
  2. Step 2: Convert to fraction form
    765.43/1,055.80 = 485.57/x
  3. Step 3: Cross multiply
    765.43x = 1,055.80 × 485.57
  4. Step 4: Simplify right side
    765.43x = 512,664.81
  5. Step 5: Solve for x
    x = 512,664.81/765.43
  6. Step 6: Final answer
    x = 669.77

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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.