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Finding the Fourth Proportional to 911.61, 1,256.90 and 778.59

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Solution

The fourth proportional to 911.61, 1,256.90 and 778.59 is: 1,073.49

Step by Step Solution

  1. Step 1: Write the proportion equation
    911.61 : 1,256.90 = 778.59 : x
  2. Step 2: Convert to fraction form
    911.61/1,256.90 = 778.59/x
  3. Step 3: Cross multiply
    911.61x = 1,256.90 × 778.59
  4. Step 4: Simplify right side
    911.61x = 978,605.88
  5. Step 5: Solve for x
    x = 978,605.88/911.61
  6. Step 6: Final answer
    x = 1,073.49

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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.