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Finding the Fourth Proportional to 687.38, 1,028.60 and 427.16

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Solution

The fourth proportional to 687.38, 1,028.60 and 427.16 is: 639.21

Step by Step Solution

  1. Step 1: Write the proportion equation
    687.38 : 1,028.60 = 427.16 : x
  2. Step 2: Convert to fraction form
    687.38/1,028.60 = 427.16/x
  3. Step 3: Cross multiply
    687.38x = 1,028.60 × 427.16
  4. Step 4: Simplify right side
    687.38x = 439,376.78
  5. Step 5: Solve for x
    x = 439,376.78/687.38
  6. Step 6: Final answer
    x = 639.21

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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.