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Finding the Fourth Proportional to 853.60, 1,280.40 and 421.60

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Solution

The fourth proportional to 853.60, 1,280.40 and 421.60 is: 632.40

Step by Step Solution

  1. Step 1: Write the proportion equation
    853.60 : 1,280.40 = 421.60 : x
  2. Step 2: Convert to fraction form
    853.60/1,280.40 = 421.60/x
  3. Step 3: Cross multiply
    853.60x = 1,280.40 × 421.60
  4. Step 4: Simplify right side
    853.60x = 539,816.64
  5. Step 5: Solve for x
    x = 539,816.64/853.60
  6. Step 6: Final answer
    x = 632.40

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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.