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Finding the Fourth Proportional to 100.79, 139.01 and 65.76

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Solution

The fourth proportional to 100.79, 139.01 and 65.76 is: 90.70

Step by Step Solution

  1. Step 1: Write the proportion equation
    100.79 : 139.01 = 65.76 : x
  2. Step 2: Convert to fraction form
    100.79/139.01 = 65.76/x
  3. Step 3: Cross multiply
    100.79x = 139.01 × 65.76
  4. Step 4: Simplify right side
    100.79x = 9,141.21
  5. Step 5: Solve for x
    x = 9,141.21/100.79
  6. Step 6: Final answer
    x = 90.70

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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.