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Finding the Fourth Proportional to 72.88, 100.48 and 61.78

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Solution

The fourth proportional to 72.88, 100.48 and 61.78 is: 85.17

Step by Step Solution

  1. Step 1: Write the proportion equation
    72.88 : 100.48 = 61.78 : x
  2. Step 2: Convert to fraction form
    72.88/100.48 = 61.78/x
  3. Step 3: Cross multiply
    72.88x = 100.48 × 61.78
  4. Step 4: Simplify right side
    72.88x = 6,206.84
  5. Step 5: Solve for x
    x = 6,206.84/72.88
  6. Step 6: Final answer
    x = 85.17

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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.