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Finding the Fourth Proportional to 782.40, 1,078.20 and 657.60

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Solution

The fourth proportional to 782.40, 1,078.20 and 657.60 is: 906.22

Step by Step Solution

  1. Step 1: Write the proportion equation
    782.40 : 1,078.20 = 657.60 : x
  2. Step 2: Convert to fraction form
    782.40/1,078.20 = 657.60/x
  3. Step 3: Cross multiply
    782.40x = 1,078.20 × 657.60
  4. Step 4: Simplify right side
    782.40x = 709,024.32
  5. Step 5: Solve for x
    x = 709,024.32/782.40
  6. Step 6: Final answer
    x = 906.22

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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.