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Finding the Fourth Proportional to 909.90, 1,256.13 and 644.40

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Solution

The fourth proportional to 909.90, 1,256.13 and 644.40 is: 889.60

Step by Step Solution

  1. Step 1: Write the proportion equation
    909.90 : 1,256.13 = 644.40 : x
  2. Step 2: Convert to fraction form
    909.90/1,256.13 = 644.40/x
  3. Step 3: Cross multiply
    909.90x = 1,256.13 × 644.40
  4. Step 4: Simplify right side
    909.90x = 809,450.17
  5. Step 5: Solve for x
    x = 809,450.17/909.90
  6. Step 6: Final answer
    x = 889.60

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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.