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Finding the Fourth Proportional to 715.72, 987.78 and 405.16

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Solution

The fourth proportional to 715.72, 987.78 and 405.16 is: 559.17

Step by Step Solution

  1. Step 1: Write the proportion equation
    715.72 : 987.78 = 405.16 : x
  2. Step 2: Convert to fraction form
    715.72/987.78 = 405.16/x
  3. Step 3: Cross multiply
    715.72x = 987.78 × 405.16
  4. Step 4: Simplify right side
    715.72x = 400,208.94
  5. Step 5: Solve for x
    x = 400,208.94/715.72
  6. Step 6: Final answer
    x = 559.17

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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.