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Finding the Fourth Proportional to 969.78, 1,455.20 and 421.97

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Solution

The fourth proportional to 969.78, 1,455.20 and 421.97 is: 633.19

Step by Step Solution

  1. Step 1: Write the proportion equation
    969.78 : 1,455.20 = 421.97 : x
  2. Step 2: Convert to fraction form
    969.78/1,455.20 = 421.97/x
  3. Step 3: Cross multiply
    969.78x = 1,455.20 × 421.97
  4. Step 4: Simplify right side
    969.78x = 614,050.74
  5. Step 5: Solve for x
    x = 614,050.74/969.78
  6. Step 6: Final answer
    x = 633.19

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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.