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Finding the Fourth Proportional to 1,109.80, 1,531.42 and 644

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Solution

The fourth proportional to 1,109.80, 1,531.42 and 644 is: 888.66

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,109.80 : 1,531.42 = 644 : x
  2. Step 2: Convert to fraction form
    1,109.80/1,531.42 = 644/x
  3. Step 3: Cross multiply
    1,109.80x = 1,531.42 × 644
  4. Step 4: Simplify right side
    1,109.80x = 986,234.48
  5. Step 5: Solve for x
    x = 986,234.48/1,109.80
  6. Step 6: Final answer
    x = 888.66

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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.