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Finding the Fourth Proportional to 428.16, 643.28 and 274.39

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Solution

The fourth proportional to 428.16, 643.28 and 274.39 is: 412.25

Step by Step Solution

  1. Step 1: Write the proportion equation
    428.16 : 643.28 = 274.39 : x
  2. Step 2: Convert to fraction form
    428.16/643.28 = 274.39/x
  3. Step 3: Cross multiply
    428.16x = 643.28 × 274.39
  4. Step 4: Simplify right side
    428.16x = 176,509.60
  5. Step 5: Solve for x
    x = 176,509.60/428.16
  6. Step 6: Final answer
    x = 412.25

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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.