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Finding the Fourth Proportional to 840.40, 1,260.32 and 407.28

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Solution

The fourth proportional to 840.40, 1,260.32 and 407.28 is: 610.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    840.40 : 1,260.32 = 407.28 : x
  2. Step 2: Convert to fraction form
    840.40/1,260.32 = 407.28/x
  3. Step 3: Cross multiply
    840.40x = 1,260.32 × 407.28
  4. Step 4: Simplify right side
    840.40x = 513,303.13
  5. Step 5: Solve for x
    x = 513,303.13/840.40
  6. Step 6: Final answer
    x = 610.78

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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.