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Finding the Fourth Proportional to 90.66, 124.74 and 78.36

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Solution

The fourth proportional to 90.66, 124.74 and 78.36 is: 107.82

Step by Step Solution

  1. Step 1: Write the proportion equation
    90.66 : 124.74 = 78.36 : x
  2. Step 2: Convert to fraction form
    90.66/124.74 = 78.36/x
  3. Step 3: Cross multiply
    90.66x = 124.74 × 78.36
  4. Step 4: Simplify right side
    90.66x = 9,774.63
  5. Step 5: Solve for x
    x = 9,774.63/90.66
  6. Step 6: Final answer
    x = 107.82

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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.