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Finding the Fourth Proportional to 1,115.56, 1,539.48 and 643.36

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Solution

The fourth proportional to 1,115.56, 1,539.48 and 643.36 is: 887.84

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,115.56 : 1,539.48 = 643.36 : x
  2. Step 2: Convert to fraction form
    1,115.56/1,539.48 = 643.36/x
  3. Step 3: Cross multiply
    1,115.56x = 1,539.48 × 643.36
  4. Step 4: Simplify right side
    1,115.56x = 990,439.85
  5. Step 5: Solve for x
    x = 990,439.85/1,115.56
  6. Step 6: Final answer
    x = 887.84

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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.