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Finding the Fourth Proportional to 1,223.90, 1,688.96 and 664.36

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Solution

The fourth proportional to 1,223.90, 1,688.96 and 664.36 is: 916.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,223.90 : 1,688.96 = 664.36 : x
  2. Step 2: Convert to fraction form
    1,223.90/1,688.96 = 664.36/x
  3. Step 3: Cross multiply
    1,223.90x = 1,688.96 × 664.36
  4. Step 4: Simplify right side
    1,223.90x = 1,122,077.47
  5. Step 5: Solve for x
    x = 1,122,077.47/1,223.90
  6. Step 6: Final answer
    x = 916.80

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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.