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Finding the Fourth Proportional to 861.96, 1,187.38 and 687

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Solution

The fourth proportional to 861.96, 1,187.38 and 687 is: 946.37

Step by Step Solution

  1. Step 1: Write the proportion equation
    861.96 : 1,187.38 = 687 : x
  2. Step 2: Convert to fraction form
    861.96/1,187.38 = 687/x
  3. Step 3: Cross multiply
    861.96x = 1,187.38 × 687
  4. Step 4: Simplify right side
    861.96x = 815,730.06
  5. Step 5: Solve for x
    x = 815,730.06/861.96
  6. Step 6: Final answer
    x = 946.37

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1.5x scale

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.