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Finding the Fourth Proportional to 715.45, 986.90 and 420.66

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Solution

The fourth proportional to 715.45, 986.90 and 420.66 is: 580.26

Step by Step Solution

  1. Step 1: Write the proportion equation
    715.45 : 986.90 = 420.66 : x
  2. Step 2: Convert to fraction form
    715.45/986.90 = 420.66/x
  3. Step 3: Cross multiply
    715.45x = 986.90 × 420.66
  4. Step 4: Simplify right side
    715.45x = 415,144.42
  5. Step 5: Solve for x
    x = 415,144.42/715.45
  6. Step 6: Final answer
    x = 580.26

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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.