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Finding the Fourth Proportional to 971.76, 1,340.88 and 640.32

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Solution

The fourth proportional to 971.76, 1,340.88 and 640.32 is: 883.54

Step by Step Solution

  1. Step 1: Write the proportion equation
    971.76 : 1,340.88 = 640.32 : x
  2. Step 2: Convert to fraction form
    971.76/1,340.88 = 640.32/x
  3. Step 3: Cross multiply
    971.76x = 1,340.88 × 640.32
  4. Step 4: Simplify right side
    971.76x = 858,592.28
  5. Step 5: Solve for x
    x = 858,592.28/971.76
  6. Step 6: Final answer
    x = 883.54

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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.