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Finding the Fourth Proportional to 669.90, 1,006.40 and 642.22

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Solution

The fourth proportional to 669.90, 1,006.40 and 642.22 is: 964.81

Step by Step Solution

  1. Step 1: Write the proportion equation
    669.90 : 1,006.40 = 642.22 : x
  2. Step 2: Convert to fraction form
    669.90/1,006.40 = 642.22/x
  3. Step 3: Cross multiply
    669.90x = 1,006.40 × 642.22
  4. Step 4: Simplify right side
    669.90x = 646,331.35
  5. Step 5: Solve for x
    x = 646,331.35/669.90
  6. Step 6: Final answer
    x = 964.81

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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.