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Finding the Fourth Proportional to 915.72, 1,373.78 and 428.50

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Solution

The fourth proportional to 915.72, 1,373.78 and 428.50 is: 642.84

Step by Step Solution

  1. Step 1: Write the proportion equation
    915.72 : 1,373.78 = 428.50 : x
  2. Step 2: Convert to fraction form
    915.72/1,373.78 = 428.50/x
  3. Step 3: Cross multiply
    915.72x = 1,373.78 × 428.50
  4. Step 4: Simplify right side
    915.72x = 588,664.73
  5. Step 5: Solve for x
    x = 588,664.73/915.72
  6. Step 6: Final answer
    x = 642.84

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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.