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Finding the Fourth Proportional to 715.78, 987.78 and 401.05

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Solution

The fourth proportional to 715.78, 987.78 and 401.05 is: 553.45

Step by Step Solution

  1. Step 1: Write the proportion equation
    715.78 : 987.78 = 401.05 : x
  2. Step 2: Convert to fraction form
    715.78/987.78 = 401.05/x
  3. Step 3: Cross multiply
    715.78x = 987.78 × 401.05
  4. Step 4: Simplify right side
    715.78x = 396,149.17
  5. Step 5: Solve for x
    x = 396,149.17/715.78
  6. Step 6: Final answer
    x = 553.45

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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.