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Finding the Fourth Proportional to 1,109.64, 1,531.26 and 643.90

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Solution

The fourth proportional to 1,109.64, 1,531.26 and 643.90 is: 888.56

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,109.64 : 1,531.26 = 643.90 : x
  2. Step 2: Convert to fraction form
    1,109.64/1,531.26 = 643.90/x
  3. Step 3: Cross multiply
    1,109.64x = 1,531.26 × 643.90
  4. Step 4: Simplify right side
    1,109.64x = 985,978.31
  5. Step 5: Solve for x
    x = 985,978.31/1,109.64
  6. Step 6: Final answer
    x = 888.56

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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.