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Finding the Fourth Proportional to 911.76, 1,256.86 and 645.36

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Solution

The fourth proportional to 911.76, 1,256.86 and 645.36 is: 889.63

Step by Step Solution

  1. Step 1: Write the proportion equation
    911.76 : 1,256.86 = 645.36 : x
  2. Step 2: Convert to fraction form
    911.76/1,256.86 = 645.36/x
  3. Step 3: Cross multiply
    911.76x = 1,256.86 × 645.36
  4. Step 4: Simplify right side
    911.76x = 811,127.17
  5. Step 5: Solve for x
    x = 811,127.17/911.76
  6. Step 6: Final answer
    x = 889.63

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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.