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Finding the Fourth Proportional to 715.86, 987.56 and 420.99

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Solution

The fourth proportional to 715.86, 987.56 and 420.99 is: 580.77

Step by Step Solution

  1. Step 1: Write the proportion equation
    715.86 : 987.56 = 420.99 : x
  2. Step 2: Convert to fraction form
    715.86/987.56 = 420.99/x
  3. Step 3: Cross multiply
    715.86x = 987.56 × 420.99
  4. Step 4: Simplify right side
    715.86x = 415,752.88
  5. Step 5: Solve for x
    x = 415,752.88/715.86
  6. Step 6: Final answer
    x = 580.77

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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.