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Finding the Fourth Proportional to 715.54, 987.09 and 420.64

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Solution

The fourth proportional to 715.54, 987.09 and 420.64 is: 580.27

Step by Step Solution

  1. Step 1: Write the proportion equation
    715.54 : 987.09 = 420.64 : x
  2. Step 2: Convert to fraction form
    715.54/987.09 = 420.64/x
  3. Step 3: Cross multiply
    715.54x = 987.09 × 420.64
  4. Step 4: Simplify right side
    715.54x = 415,209.54
  5. Step 5: Solve for x
    x = 415,209.54/715.54
  6. Step 6: Final answer
    x = 580.27

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.