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Finding the Fourth Proportional to 278.50, 417.75 and 86.13

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Solution

The fourth proportional to 278.50, 417.75 and 86.13 is: 129.20

Step by Step Solution

  1. Step 1: Write the proportion equation
    278.50 : 417.75 = 86.13 : x
  2. Step 2: Convert to fraction form
    278.50/417.75 = 86.13/x
  3. Step 3: Cross multiply
    278.50x = 417.75 × 86.13
  4. Step 4: Simplify right side
    278.50x = 35,980.81
  5. Step 5: Solve for x
    x = 35,980.81/278.50
  6. Step 6: Final answer
    x = 129.20

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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.