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Finding the Fourth Proportional to 428.64, 642.96 and 258.72

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Solution

The fourth proportional to 428.64, 642.96 and 258.72 is: 388.08

Step by Step Solution

  1. Step 1: Write the proportion equation
    428.64 : 642.96 = 258.72 : x
  2. Step 2: Convert to fraction form
    428.64/642.96 = 258.72/x
  3. Step 3: Cross multiply
    428.64x = 642.96 × 258.72
  4. Step 4: Simplify right side
    428.64x = 166,346.61
  5. Step 5: Solve for x
    x = 166,346.61/428.64
  6. Step 6: Final answer
    x = 388.08

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.