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Finding the Fourth Proportional to 687.15, 947.90 and 421.47

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Solution

The fourth proportional to 687.15, 947.90 and 421.47 is: 581.41

Step by Step Solution

  1. Step 1: Write the proportion equation
    687.15 : 947.90 = 421.47 : x
  2. Step 2: Convert to fraction form
    687.15/947.90 = 421.47/x
  3. Step 3: Cross multiply
    687.15x = 947.90 × 421.47
  4. Step 4: Simplify right side
    687.15x = 399,512.47
  5. Step 5: Solve for x
    x = 399,512.47/687.15
  6. Step 6: Final answer
    x = 581.41

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These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.