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Finding the Fourth Proportional to 110.72, 165.90 and 78.20

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Solution

The fourth proportional to 110.72, 165.90 and 78.20 is: 117.17

Step by Step Solution

  1. Step 1: Write the proportion equation
    110.72 : 165.90 = 78.20 : x
  2. Step 2: Convert to fraction form
    110.72/165.90 = 78.20/x
  3. Step 3: Cross multiply
    110.72x = 165.90 × 78.20
  4. Step 4: Simplify right side
    110.72x = 12,973.38
  5. Step 5: Solve for x
    x = 12,973.38/110.72
  6. Step 6: Final answer
    x = 117.17

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.