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Finding the Fourth Proportional to 715.56, 987.30 and 421

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Solution

The fourth proportional to 715.56, 987.30 and 421 is: 580.88

Step by Step Solution

  1. Step 1: Write the proportion equation
    715.56 : 987.30 = 421 : x
  2. Step 2: Convert to fraction form
    715.56/987.30 = 421/x
  3. Step 3: Cross multiply
    715.56x = 987.30 × 421
  4. Step 4: Simplify right side
    715.56x = 415,653.30
  5. Step 5: Solve for x
    x = 415,653.30/715.56
  6. Step 6: Final answer
    x = 580.88

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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.