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Finding the Fourth Proportional to 819.18, 1,130.40 and 642.30

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Solution

The fourth proportional to 819.18, 1,130.40 and 642.30 is: 886.32

Step by Step Solution

  1. Step 1: Write the proportion equation
    819.18 : 1,130.40 = 642.30 : x
  2. Step 2: Convert to fraction form
    819.18/1,130.40 = 642.30/x
  3. Step 3: Cross multiply
    819.18x = 1,130.40 × 642.30
  4. Step 4: Simplify right side
    819.18x = 726,055.92
  5. Step 5: Solve for x
    x = 726,055.92/819.18
  6. Step 6: Final answer
    x = 886.32

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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.