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Finding the Fourth Proportional to 305, 420.76 and 217.72

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Solution

The fourth proportional to 305, 420.76 and 217.72 is: 300.35

Step by Step Solution

  1. Step 1: Write the proportion equation
    305 : 420.76 = 217.72 : x
  2. Step 2: Convert to fraction form
    305/420.76 = 217.72/x
  3. Step 3: Cross multiply
    305x = 420.76 × 217.72
  4. Step 4: Simplify right side
    305x = 91,607.87
  5. Step 5: Solve for x
    x = 91,607.87/305
  6. Step 6: Final answer
    x = 300.35

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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.