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Finding the Fourth Proportional to 100.91, 139.23 and 56.64

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Solution

The fourth proportional to 100.91, 139.23 and 56.64 is: 78.15

Step by Step Solution

  1. Step 1: Write the proportion equation
    100.91 : 139.23 = 56.64 : x
  2. Step 2: Convert to fraction form
    100.91/139.23 = 56.64/x
  3. Step 3: Cross multiply
    100.91x = 139.23 × 56.64
  4. Step 4: Simplify right side
    100.91x = 7,885.99
  5. Step 5: Solve for x
    x = 7,885.99/100.91
  6. Step 6: Final answer
    x = 78.15

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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.