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Finding the Fourth Proportional to 821.10, 1,231.65 and 785.55

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Solution

The fourth proportional to 821.10, 1,231.65 and 785.55 is: 1,178.33

Step by Step Solution

  1. Step 1: Write the proportion equation
    821.10 : 1,231.65 = 785.55 : x
  2. Step 2: Convert to fraction form
    821.10/1,231.65 = 785.55/x
  3. Step 3: Cross multiply
    821.10x = 1,231.65 × 785.55
  4. Step 4: Simplify right side
    821.10x = 967,522.66
  5. Step 5: Solve for x
    x = 967,522.66/821.10
  6. Step 6: Final answer
    x = 1,178.33

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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.