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Finding the Fourth Proportional to 100, 137.88 and 66.78

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Solution

The fourth proportional to 100, 137.88 and 66.78 is: 92.08

Step by Step Solution

  1. Step 1: Write the proportion equation
    100 : 137.88 = 66.78 : x
  2. Step 2: Convert to fraction form
    100/137.88 = 66.78/x
  3. Step 3: Cross multiply
    100x = 137.88 × 66.78
  4. Step 4: Simplify right side
    100x = 9,207.63
  5. Step 5: Solve for x
    x = 9,207.63/100
  6. Step 6: Final answer
    x = 92.08

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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.