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Finding the Fourth Proportional to 820.40, 1,228.40 and 647.39

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Solution

The fourth proportional to 820.40, 1,228.40 and 647.39 is: 969.36

Step by Step Solution

  1. Step 1: Write the proportion equation
    820.40 : 1,228.40 = 647.39 : x
  2. Step 2: Convert to fraction form
    820.40/1,228.40 = 647.39/x
  3. Step 3: Cross multiply
    820.40x = 1,228.40 × 647.39
  4. Step 4: Simplify right side
    820.40x = 795,256.14
  5. Step 5: Solve for x
    x = 795,256.14/820.40
  6. Step 6: Final answer
    x = 969.36

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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.