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Finding the Fourth Proportional to 715.82, 987.80 and 421.11

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Solution

The fourth proportional to 715.82, 987.80 and 421.11 is: 581.11

Step by Step Solution

  1. Step 1: Write the proportion equation
    715.82 : 987.80 = 421.11 : x
  2. Step 2: Convert to fraction form
    715.82/987.80 = 421.11/x
  3. Step 3: Cross multiply
    715.82x = 987.80 × 421.11
  4. Step 4: Simplify right side
    715.82x = 415,970.35
  5. Step 5: Solve for x
    x = 415,970.35/715.82
  6. Step 6: Final answer
    x = 581.11

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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.