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Finding the Fourth Proportional to 821.68, 1,231.76 and 431.60

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Solution

The fourth proportional to 821.68, 1,231.76 and 431.60 is: 647.00

Step by Step Solution

  1. Step 1: Write the proportion equation
    821.68 : 1,231.76 = 431.60 : x
  2. Step 2: Convert to fraction form
    821.68/1,231.76 = 431.60/x
  3. Step 3: Cross multiply
    821.68x = 1,231.76 × 431.60
  4. Step 4: Simplify right side
    821.68x = 531,627.62
  5. Step 5: Solve for x
    x = 531,627.62/821.68
  6. Step 6: Final answer
    x = 647.00

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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.