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Finding the Fourth Proportional to 280.42, 420.54 and 85.35

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Solution

The fourth proportional to 280.42, 420.54 and 85.35 is: 128.00

Step by Step Solution

  1. Step 1: Write the proportion equation
    280.42 : 420.54 = 85.35 : x
  2. Step 2: Convert to fraction form
    280.42/420.54 = 85.35/x
  3. Step 3: Cross multiply
    280.42x = 420.54 × 85.35
  4. Step 4: Simplify right side
    280.42x = 35,893.09
  5. Step 5: Solve for x
    x = 35,893.09/280.42
  6. Step 6: Final answer
    x = 128.00

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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.