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Finding the Fourth Proportional to 1,115.08, 1,538.98 and 642.89

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Solution

The fourth proportional to 1,115.08, 1,538.98 and 642.89 is: 887.28

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,115.08 : 1,538.98 = 642.89 : x
  2. Step 2: Convert to fraction form
    1,115.08/1,538.98 = 642.89/x
  3. Step 3: Cross multiply
    1,115.08x = 1,538.98 × 642.89
  4. Step 4: Simplify right side
    1,115.08x = 989,388.44
  5. Step 5: Solve for x
    x = 989,388.44/1,115.08
  6. Step 6: Final answer
    x = 887.28

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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.