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Finding the Fourth Proportional to 309.76, 427.28 and 257.00

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Solution

The fourth proportional to 309.76, 427.28 and 257.00 is: 354.50

Step by Step Solution

  1. Step 1: Write the proportion equation
    309.76 : 427.28 = 257.00 : x
  2. Step 2: Convert to fraction form
    309.76/427.28 = 257.00/x
  3. Step 3: Cross multiply
    309.76x = 427.28 × 257.00
  4. Step 4: Simplify right side
    309.76x = 109,807.54
  5. Step 5: Solve for x
    x = 109,807.54/309.76
  6. Step 6: Final answer
    x = 354.50

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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.