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Finding the Fourth Proportional to 280.36, 420.54 and 85.36

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Solution

The fourth proportional to 280.36, 420.54 and 85.36 is: 128.04

Step by Step Solution

  1. Step 1: Write the proportion equation
    280.36 : 420.54 = 85.36 : x
  2. Step 2: Convert to fraction form
    280.36/420.54 = 85.36/x
  3. Step 3: Cross multiply
    280.36x = 420.54 × 85.36
  4. Step 4: Simplify right side
    280.36x = 35,896.03
  5. Step 5: Solve for x
    x = 35,896.03/280.36
  6. Step 6: Final answer
    x = 128.04

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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.