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Finding the Fourth Proportional to 840.40, 1,259.80 and 655.20

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Solution

The fourth proportional to 840.40, 1,259.80 and 655.20 is: 982.18

Step by Step Solution

  1. Step 1: Write the proportion equation
    840.40 : 1,259.80 = 655.20 : x
  2. Step 2: Convert to fraction form
    840.40/1,259.80 = 655.20/x
  3. Step 3: Cross multiply
    840.40x = 1,259.80 × 655.20
  4. Step 4: Simplify right side
    840.40x = 825,420.96
  5. Step 5: Solve for x
    x = 825,420.96/840.40
  6. Step 6: Final answer
    x = 982.18

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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.