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Finding the Fourth Proportional to 1,109.78, 1,531.75 and 644.30

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Solution

The fourth proportional to 1,109.78, 1,531.75 and 644.30 is: 889.28

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,109.78 : 1,531.75 = 644.30 : x
  2. Step 2: Convert to fraction form
    1,109.78/1,531.75 = 644.30/x
  3. Step 3: Cross multiply
    1,109.78x = 1,531.75 × 644.30
  4. Step 4: Simplify right side
    1,109.78x = 986,906.53
  5. Step 5: Solve for x
    x = 986,906.53/1,109.78
  6. Step 6: Final answer
    x = 889.28

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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.