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Finding the Fourth Proportional to 664.50, 916.70 and 398.78

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Solution

The fourth proportional to 664.50, 916.70 and 398.78 is: 550.13

Step by Step Solution

  1. Step 1: Write the proportion equation
    664.50 : 916.70 = 398.78 : x
  2. Step 2: Convert to fraction form
    664.50/916.70 = 398.78/x
  3. Step 3: Cross multiply
    664.50x = 916.70 × 398.78
  4. Step 4: Simplify right side
    664.50x = 365,561.63
  5. Step 5: Solve for x
    x = 365,561.63/664.50
  6. Step 6: Final answer
    x = 550.13

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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.