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Finding the Fourth Proportional to 915.71, 1,372.93 and 428.90

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Solution

The fourth proportional to 915.71, 1,372.93 and 428.90 is: 643.05

Step by Step Solution

  1. Step 1: Write the proportion equation
    915.71 : 1,372.93 = 428.90 : x
  2. Step 2: Convert to fraction form
    915.71/1,372.93 = 428.90/x
  3. Step 3: Cross multiply
    915.71x = 1,372.93 × 428.90
  4. Step 4: Simplify right side
    915.71x = 588,841.74
  5. Step 5: Solve for x
    x = 588,841.74/915.71
  6. Step 6: Final answer
    x = 643.05

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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.