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Finding the Fourth Proportional to 774.78, 1,162.56 and 390

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Solution

The fourth proportional to 774.78, 1,162.56 and 390 is: 585.20

Step by Step Solution

  1. Step 1: Write the proportion equation
    774.78 : 1,162.56 = 390 : x
  2. Step 2: Convert to fraction form
    774.78/1,162.56 = 390/x
  3. Step 3: Cross multiply
    774.78x = 1,162.56 × 390
  4. Step 4: Simplify right side
    774.78x = 453,398.40
  5. Step 5: Solve for x
    x = 453,398.40/774.78
  6. Step 6: Final answer
    x = 585.20

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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.