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Finding the Fourth Proportional to 780.12, 1,076.76 and 518.40

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Solution

The fourth proportional to 780.12, 1,076.76 and 518.40 is: 715.52

Step by Step Solution

  1. Step 1: Write the proportion equation
    780.12 : 1,076.76 = 518.40 : x
  2. Step 2: Convert to fraction form
    780.12/1,076.76 = 518.40/x
  3. Step 3: Cross multiply
    780.12x = 1,076.76 × 518.40
  4. Step 4: Simplify right side
    780.12x = 558,192.38
  5. Step 5: Solve for x
    x = 558,192.38/780.12
  6. Step 6: Final answer
    x = 715.52

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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.