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Finding the Fourth Proportional to 715.75, 987.92 and 405.43

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Solution

The fourth proportional to 715.75, 987.92 and 405.43 is: 559.60

Step by Step Solution

  1. Step 1: Write the proportion equation
    715.75 : 987.92 = 405.43 : x
  2. Step 2: Convert to fraction form
    715.75/987.92 = 405.43/x
  3. Step 3: Cross multiply
    715.75x = 987.92 × 405.43
  4. Step 4: Simplify right side
    715.75x = 400,532.41
  5. Step 5: Solve for x
    x = 400,532.41/715.75
  6. Step 6: Final answer
    x = 559.60

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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.