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Finding the Fourth Proportional to 911.86, 1,257.68 and 645.77

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Solution

The fourth proportional to 911.86, 1,257.68 and 645.77 is: 890.68

Step by Step Solution

  1. Step 1: Write the proportion equation
    911.86 : 1,257.68 = 645.77 : x
  2. Step 2: Convert to fraction form
    911.86/1,257.68 = 645.77/x
  3. Step 3: Cross multiply
    911.86x = 1,257.68 × 645.77
  4. Step 4: Simplify right side
    911.86x = 812,173.14
  5. Step 5: Solve for x
    x = 812,173.14/911.86
  6. Step 6: Final answer
    x = 890.68

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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.