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Finding the Fourth Proportional to 155.95, 215.21 and 100.72

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Solution

The fourth proportional to 155.95, 215.21 and 100.72 is: 138.99

Step by Step Solution

  1. Step 1: Write the proportion equation
    155.95 : 215.21 = 100.72 : x
  2. Step 2: Convert to fraction form
    155.95/215.21 = 100.72/x
  3. Step 3: Cross multiply
    155.95x = 215.21 × 100.72
  4. Step 4: Simplify right side
    155.95x = 21,675.95
  5. Step 5: Solve for x
    x = 21,675.95/155.95
  6. Step 6: Final answer
    x = 138.99

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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.