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Finding the Fourth Proportional to 715.90, 987.68 and 421.17

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Solution

The fourth proportional to 715.90, 987.68 and 421.17 is: 581.06

Step by Step Solution

  1. Step 1: Write the proportion equation
    715.90 : 987.68 = 421.17 : x
  2. Step 2: Convert to fraction form
    715.90/987.68 = 421.17/x
  3. Step 3: Cross multiply
    715.90x = 987.68 × 421.17
  4. Step 4: Simplify right side
    715.90x = 415,980.03
  5. Step 5: Solve for x
    x = 415,980.03/715.90
  6. Step 6: Final answer
    x = 581.06

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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.