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Finding the Fourth Proportional to 891.78, 1,336.76 and 428.87

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Solution

The fourth proportional to 891.78, 1,336.76 and 428.87 is: 642.86

Step by Step Solution

  1. Step 1: Write the proportion equation
    891.78 : 1,336.76 = 428.87 : x
  2. Step 2: Convert to fraction form
    891.78/1,336.76 = 428.87/x
  3. Step 3: Cross multiply
    891.78x = 1,336.76 × 428.87
  4. Step 4: Simplify right side
    891.78x = 573,287.43
  5. Step 5: Solve for x
    x = 573,287.43/891.78
  6. Step 6: Final answer
    x = 642.86

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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.