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Finding the Fourth Proportional to 858.90, 1,189.17 and 815.70

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Solution

The fourth proportional to 858.90, 1,189.17 and 815.70 is: 1,129.36

Step by Step Solution

  1. Step 1: Write the proportion equation
    858.90 : 1,189.17 = 815.70 : x
  2. Step 2: Convert to fraction form
    858.90/1,189.17 = 815.70/x
  3. Step 3: Cross multiply
    858.90x = 1,189.17 × 815.70
  4. Step 4: Simplify right side
    858.90x = 970,005.97
  5. Step 5: Solve for x
    x = 970,005.97/858.90
  6. Step 6: Final answer
    x = 1,129.36

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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.