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Finding the Fourth Proportional to 715.64, 987.58 and 420.85

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Solution

The fourth proportional to 715.64, 987.58 and 420.85 is: 580.77

Step by Step Solution

  1. Step 1: Write the proportion equation
    715.64 : 987.58 = 420.85 : x
  2. Step 2: Convert to fraction form
    715.64/987.58 = 420.85/x
  3. Step 3: Cross multiply
    715.64x = 987.58 × 420.85
  4. Step 4: Simplify right side
    715.64x = 415,623.04
  5. Step 5: Solve for x
    x = 415,623.04/715.64
  6. Step 6: Final answer
    x = 580.77

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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.