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Finding the Fourth Proportional to 715.48, 987.38 and 405

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Solution

The fourth proportional to 715.48, 987.38 and 405 is: 558.91

Step by Step Solution

  1. Step 1: Write the proportion equation
    715.48 : 987.38 = 405 : x
  2. Step 2: Convert to fraction form
    715.48/987.38 = 405/x
  3. Step 3: Cross multiply
    715.48x = 987.38 × 405
  4. Step 4: Simplify right side
    715.48x = 399,888.90
  5. Step 5: Solve for x
    x = 399,888.90/715.48
  6. Step 6: Final answer
    x = 558.91

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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.