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Finding the Fourth Proportional to 1,223.78, 1,688.90 and 699.80

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Solution

The fourth proportional to 1,223.78, 1,688.90 and 699.80 is: 965.77

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,223.78 : 1,688.90 = 699.80 : x
  2. Step 2: Convert to fraction form
    1,223.78/1,688.90 = 699.80/x
  3. Step 3: Cross multiply
    1,223.78x = 1,688.90 × 699.80
  4. Step 4: Simplify right side
    1,223.78x = 1,181,892.22
  5. Step 5: Solve for x
    x = 1,181,892.22/1,223.78
  6. Step 6: Final answer
    x = 965.77

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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.