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Finding the Fourth Proportional to 740.40, 1,021.70 and 408.78

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Solution

The fourth proportional to 740.40, 1,021.70 and 408.78 is: 564.09

Step by Step Solution

  1. Step 1: Write the proportion equation
    740.40 : 1,021.70 = 408.78 : x
  2. Step 2: Convert to fraction form
    740.40/1,021.70 = 408.78/x
  3. Step 3: Cross multiply
    740.40x = 1,021.70 × 408.78
  4. Step 4: Simplify right side
    740.40x = 417,650.53
  5. Step 5: Solve for x
    x = 417,650.53/740.40
  6. Step 6: Final answer
    x = 564.09

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.