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Finding the Fourth Proportional to 715.49, 987.09 and 420.65

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Solution

The fourth proportional to 715.49, 987.09 and 420.65 is: 580.33

Step by Step Solution

  1. Step 1: Write the proportion equation
    715.49 : 987.09 = 420.65 : x
  2. Step 2: Convert to fraction form
    715.49/987.09 = 420.65/x
  3. Step 3: Cross multiply
    715.49x = 987.09 × 420.65
  4. Step 4: Simplify right side
    715.49x = 415,219.41
  5. Step 5: Solve for x
    x = 415,219.41/715.49
  6. Step 6: Final answer
    x = 580.33

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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.