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Finding the Fourth Proportional to 665.78, 999 and 645.30

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Solution

The fourth proportional to 665.78, 999 and 645.30 is: 968.28

Step by Step Solution

  1. Step 1: Write the proportion equation
    665.78 : 999 = 645.30 : x
  2. Step 2: Convert to fraction form
    665.78/999 = 645.30/x
  3. Step 3: Cross multiply
    665.78x = 999 × 645.30
  4. Step 4: Simplify right side
    665.78x = 644,654.70
  5. Step 5: Solve for x
    x = 644,654.70/665.78
  6. Step 6: Final answer
    x = 968.28

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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.