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Finding the Fourth Proportional to 305.15, 420.90 and 280.34

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Solution

The fourth proportional to 305.15, 420.90 and 280.34 is: 386.66

Step by Step Solution

  1. Step 1: Write the proportion equation
    305.15 : 420.90 = 280.34 : x
  2. Step 2: Convert to fraction form
    305.15/420.90 = 280.34/x
  3. Step 3: Cross multiply
    305.15x = 420.90 × 280.34
  4. Step 4: Simplify right side
    305.15x = 117,992.34
  5. Step 5: Solve for x
    x = 117,992.34/305.15
  6. Step 6: Final answer
    x = 386.66

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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.