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Finding the Fourth Proportional to 72.20, 99.72 and 68.78

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Solution

The fourth proportional to 72.20, 99.72 and 68.78 is: 95.00

Step by Step Solution

  1. Step 1: Write the proportion equation
    72.20 : 99.72 = 68.78 : x
  2. Step 2: Convert to fraction form
    72.20/99.72 = 68.78/x
  3. Step 3: Cross multiply
    72.20x = 99.72 × 68.78
  4. Step 4: Simplify right side
    72.20x = 6,858.99
  5. Step 5: Solve for x
    x = 6,858.99/72.20
  6. Step 6: Final answer
    x = 95.00

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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.