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Finding the Fourth Proportional to 915.92, 1,371.60 and 640.72

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Solution

The fourth proportional to 915.92, 1,371.60 and 640.72 is: 959.48

Step by Step Solution

  1. Step 1: Write the proportion equation
    915.92 : 1,371.60 = 640.72 : x
  2. Step 2: Convert to fraction form
    915.92/1,371.60 = 640.72/x
  3. Step 3: Cross multiply
    915.92x = 1,371.60 × 640.72
  4. Step 4: Simplify right side
    915.92x = 878,807.35
  5. Step 5: Solve for x
    x = 878,807.35/915.92
  6. Step 6: Final answer
    x = 959.48

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.