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Finding the Fourth Proportional to 821.80, 1,232.70 and 389.80

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Solution

The fourth proportional to 821.80, 1,232.70 and 389.80 is: 584.70

Step by Step Solution

  1. Step 1: Write the proportion equation
    821.80 : 1,232.70 = 389.80 : x
  2. Step 2: Convert to fraction form
    821.80/1,232.70 = 389.80/x
  3. Step 3: Cross multiply
    821.80x = 1,232.70 × 389.80
  4. Step 4: Simplify right side
    821.80x = 480,506.46
  5. Step 5: Solve for x
    x = 480,506.46/821.80
  6. Step 6: Final answer
    x = 584.70

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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.