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Finding the Fourth Proportional to 715.84, 987.64 and 421.12

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Solution

The fourth proportional to 715.84, 987.64 and 421.12 is: 581.02

Step by Step Solution

  1. Step 1: Write the proportion equation
    715.84 : 987.64 = 421.12 : x
  2. Step 2: Convert to fraction form
    715.84/987.64 = 421.12/x
  3. Step 3: Cross multiply
    715.84x = 987.64 × 421.12
  4. Step 4: Simplify right side
    715.84x = 415,914.96
  5. Step 5: Solve for x
    x = 415,914.96/715.84
  6. Step 6: Final answer
    x = 581.02

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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.